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The  volumes  of  the  University  of  Michigan 
Studies  are  published  by  authority  of  the  Executive 
Board  of  the  Graduate  Department.  A  list  of  the 
volumes  thus  far  published  is  given  at  the  end  of 
this  volume. 


SCIENTIFIC  SERIES 


VOLUME    I 


THE  CIRCULATION  AND  SLEEP 


THE  MACMILLAN    COMPANY 

NEW  YORK  BOSTON  CHICAGO 

DALLAS  SAN    FHANCISCO 

MACMILLAN  &  CO.,  Limited 

LONDON     BOMBAY       CALCUTTA 
MELBOURNE 

THE  MACMILLAN  CO.  OF  CANADA,  Ltd. 

TORONTO 


THE  CIRCULATION  AND  SLEEP 

EXPERIMENTAL  INVESTIGATIONS 
ACCOMPANIED  BY  AN  ATLAS 


JOHN   F.  SHEPARD 

UNIVERSITY   OF   MICHIGAN 


THE  MACMILLAN  COMPANY 
1914 

AH  rights  reserved 


Copyright,  1914 
By  The  University  of  Michigan 


PREFACE 

This  volume  is  primarily  a  report  of  experimental  investigations.  Altogether 
it  was  necessary  to  study  several  hundred  records,  the  total  length  of  which 
amounted  to  about  thirty-five  hundred  feet.  Each  record  contained  from  two  to 
six  tracings  besides  indicator  lines.  Those  reproduced  were,  of  course,  selected 
to  show  typical  conditions. 

A  part  of  the  expense  of  employing  trephined  individuals  to  serve  as  subjects, 
was  met  by  a  grant  from  the  Elizabeth  Thompson  Science  Fund.  A  part  of  the 
remainder  was  paid  by  the  University  of  Michigan.  I  am  most  grateful  for  these 
grants.  I  am  indebted  to  Professors  Pillsbury  and  Lombard  for  their  aid  and 
encouragement  at  all  times,  and  for  reading  the  manuscript.  Thanks  are  due  to 
Professors  G.  L.  Jackson,  F.  C.  Dockeray,  and  H.  H.  Woodrow,  and  to  Mr.  C. 
E.  Galloway  for  assisting  in  the  experiments.  I  am  especially  indebted  to  my 
wife,  who  has  been  of  the  greatest  service  in  the  preparation  of  the  manuscript. 
Mr.  W.  C.  Hollands  has  given  aid  in  matters  of  publication.  I  wish  finally,  to 
express  my  thorough  appreciation  of  the  action  of  the  University  in  providing  for 
publication. 

John  F.  Shepard. 

Ann  Arbor,  1913. 


CONTENTS 

Chapter    I 

Page 
The  General  Problems i 

Chapter   II 
The  Volume  of  the  Brain  and  of  the  Periphery,  and  the  Breathing  Curve  ....    lO 

Chapter   III 
The  Blood  Pressure 40 

Chapter   IV 
The  Heart  Rate  and  Pulse  Transmission  Time 50 

Chapter   V 
The  Jugular  Pulse 62 

Chapter   VI 
The  Pulse  Form 64 

Chapter   VII 
General  Conclusions  and  Theory 70 

Appendix 
The  Influence  of  Some  Drugs  upon  the  Circulation 80 


CHAPTER   I 
THE  GENERAL  PROBLEM 

There  have  been  innumerable  speculations  as  to  the  nature  of  sleep,  and  there 
are  several  types  of  theories  which  may  claim  a  more  or  less  scientific  basis.  At 
present,  however,  I  shall  be  concerned  with  the  circulatory  theories  only.  I  shall 
begin  with  a  discussion  of  several  important  investigations  of  the  relations  between 
sleep  and  changes  in  the  circulation. 

Mosso  published  his  great  work,  "  Kreislauf  des  Blutes  im  Menschlichen 
Gehirn,"  in  1881.  It  is  based  upon  a  study  of  three  cases,  although  only  a  few 
curves  were  obtained  from  each.  One  was  a  woman,  a  considerable  portion  of 
whose  skull  had  been  removed  as  a  result  of  syphilitic  infection.  The  second 
was  an  epileptic  child  who  had  been  injured  and  trephined  when  eighteen  months 
old.     The  third  was  a  farmer,  trephined  on  account  of  injury  from  a  falling  brick. 

Mosso  concludes  that  in  sleep  there  is  relaxation  of  the  vessels  of  the  limbs, 
shown  by  plethysmographic  tracings  from  the  arm,  and  decrease  of  the  blood 
supply  to  the  brain.  The  heart  rate  is  in  general  lowered,  though  subject  to  great 
irregularities.  A  stimulus  that  does  not  waken  the  subject  causes  a  constriction 
of  the  vessels  of  the  arm,  and  consequent  increase  of  flow  through  the  brain. 
Abdominal  breathing  is  decreased,  chest  breathing  increased.  In  both  waking 
and  sleeping  there  are  undulations  in  the  brain  curve,  and  these  are  of  three 
types :  passive,  caused  by  alterations  in  general  blood  pressure,  in  which  there  is 
no  change  in  pulse  form;  active,  due  to  contraction  and  relaxation  of  the  brain 
vessels  themselves,  in  which  there  is  change  of  pulse  form;  and  another  type  of 
passive  wave,  due  to  change  in  venous  outflow,  in  which  the  pulse  at  the  crest  of 
the  wave  is  restricted,  being  in  this  regard  the  reverse  of  the  first  two  types. 

We  shall  see  later  that  Mosso's  criteria  of  types  of  undulation  are  entirely 
insufficient.  And  some  of  his  conclusions  in  regard  to  reactions  with  sleep  do 
not  seem  to  me  justified  by  an  examination  of  his  own  published  curves.  I 
doubt  whether  the  subject  was  actually  asleep  during  the  taking  of  the  records 
which  he  gives  in  Fig.  21,  for  the  recovery  from  the  reaction  is  altogether  too 
rapid  to  have  accompanied  an  awakening.  Taf.  V,  15  and  16,  seem  much  more 
like  accurate  plethysmographic  tracings  that  might  accompany  changes  in  the 
depth  of  sleep,  and  the  subject  was  definitely  snoring;  here  it  will  be  observed, 
both  a  break  in  snoring  and  awakening  were  accompanied  by  a  fall  of  volume. 
The  falls  of  volume  followed  by  large  pulse  in  Fig.  26  and  Taf.  IX,  38,  are 
ambiguous.  Some  other  cases  of  rise  of  the  brain  record  with  subliminal  stimuli, 
are  less  open  to  criticism.  The  evidence  for  Mosso's  view  is  very  uncertain.  It 
should  be  added  that  Mosso  himself  does  not  believe  that  cerebral  anaemia  is  the 
cause  of  sleep. 


2  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

The  next  year,  1882,  Mays  published  a  few  records  from  two  subjects.  The 
best  curves  from  one  subject  seemed  to  give  a  fall  of  the  brain  volume,  both 
with  subliminal  stimuli  during  sleep  and  vwith  awakening.  The  result  as  a  whole 
is  uncertain. 

The  investigations  of  Leonard  Hill  were  of  a  different  character.  He  worked 
almost  entirely  upon  dogs,  and  in  the  complete  experiment  four  values  were 
measured :  the  general  arterial  pressure,  the  general  venous  pressure,  the  cerebral 
venous  (torcular)  pressure,  and  the  intracranial  pressure.  It  was  found  that  the 
intracranial  pressure  is  in  all  normal  conditions  the  same  as  cerebral  venous 
pressure. 

Hill  found  that  the  amount  of  cerebro-spinal  fluid  normally  present  is  small, 
and  the  amount  of  blood  in  the  brain  must  remain  in  all  physiological  conditions 
very  nearly  the  same  (Monro-Kellie  doctrine).  On  this  basis  he  criticises  any 
method  of  studying  the  blood  supply  to  the  brain  with  an  open  cranium,  since 
this  changes  the  physical  condition  of  the  cerebral  circulation,  exposes  the  cerebral 
capillaries  to  the  air  pressure,  and  permits  alterations  of  blood  volume.  The 
vaso-motor  center  and  all  the  known  nerve  supply  to  the  carotid  and  vertebral 
arteries  were  stimulated  without  furnishing  any  evidence  of  vaso-motor  control 
within  the  brain  circulation.  Instead,  the  cerebral  venous  pressure  always  varied 
absolutely  with  general  venous  pressure  and  proportionately  with  arterial  pressure. 
Sleep,  with  its  lowered  blood  pressure,  he  concludes  is  always  due  to  cerebral 
anaemia,  accompanied  perhaps  by  venous  congestion;  and  the  blood  pressure, 
in  this  process,  is  controlled  by  the  degree  of  splanchnic  constriction  maintained 
by  the  vaso-motor  center. 

Later  I  shall  return  to  the  question  of  vaso-motor  nerve  supply  to  the  cerebral 
vessels  and  the  control  of  the  circulation  through  them.  But  the  criticism  of 
other  methods  of  investigation  and  the  adequacy  of  Hill's  method  demand  some 
consideration  here.  I  have  no  doubt  of  the  correctness  of  the  Monro-Kellie 
doctrine  within  limits.  Consequently  we  shall  agree  that  any  large  constriction 
or  relaxation  of  the  small  arteries  of  the  brain  (more  than  the  supply  of  cerebro- 
spinal fluid)  must  involve  a  change  of  opposite  character  in  other  arteries  within 
the  skull  or  more  probably  in  the  venous  system, — a  readjustment  of  the  relative 
capacities  of  the  vessels.  Now,  so  far  as  there  is  such  readjustment  it  is  true 
that  the  reaction  does  not  involve  exactly  the  same  effect  as  a  vaso-motor  response 
in  another  part  of  the  body,  in  the  hand  for  instance.  The  latter  would  mean 
a  change  in  the  total  capacity  of  the  circulatory  system,  a  rise  or  fall  of  the 
total  arterial-venous  pressure;  the  former  simply  a  change  in  the  ease  of  passage 
from  arteries  to  veins.  But  a  constriction  of  the  small  arteries  in  any  organ, 
particularly  in  the  brain,  must  cause  a  much  greater  increase  in  resistance  than 
could  be  compensated  for  by  expansion  of  the  larger  veins  by  the  same  volume ; 
and  relaxation  of  the  small  arteries  within  any  reasonable  limits,  gives  a  greater 
reduction  of  resistance  than  decrease  of  the  large  veins  by  a  corresponding  volume 
could  possibly  equalize.  As  a  result,  the  readjustment  brings  with  it  an  altera- 
tion of  the  flow,  which  is  all  that  one  could  mean  by  control  of  the  brain  circula- 


THE   GENERAL   PROBLEM  3 

tion.  Even  if  large  changes  in  total  blood  volume  in  the  closed  cranium  are 
impossible,  practically  the  same  effect  is  possible.  To  trephine  the  skull  and 
increase  the  change  of  volume  directly,  does  not  modify  the  character  of  the 
reaction  studied,  though  it  may  alter  its  degree  somewhat  by  making  unnecessary 
the  comparatively  unimportant  counter-effect  upon  the  venous  system.  I  am  not 
sure  whether  Hill  thinks  of  it  in  this  way,  but  it  is  an  error  to  interpret  the 
Monro-Kellie  doctrine  as  though  it  practically  necessitated  that  the  cerebral  vessels 
be  passive,  an  error  which  is  often  made. 

Furthermore,  in  several  records  which  I  shall  reproduce  later  in  this  work, 
and  in  scores  of  others  which  expense  prevents  my  reproducing,^  the  brain  shows 
very  marked  expansions  and  contractions  without  in  any  way  plugging  the 
trephine,  or  interfering  with  its  free  pulsations  and  changes  of  volume  by  pressing 
against  the  bone  or  the  skin  covering.  There  is  room  in  the  normal  human  skull 
for  very  significant  reactions  without  noticeable  encroachments  upon  other  vessels. 
Whether  this  space  is,  in  the  closed  cranium,  occupied  by  cerebro-spinal  fluid  or 
soft-walled  veins,  makes  no  difference. 

The  objection  that  investigations  recording  volume  changes  through  a  trephine 
are  invalidated  because  the  opening  allows  the  atmospheric  pressure  to  act  upon 
the  cerebral  vessels,  is  a  more  obvious  error  The  atmospheric  pressure  is  always 
acting  upon  the  brain  through  the  veins  of  the  neck,  in  which  the  resistance  of 
the  jugular  is  negligible.  Otherwise  such  trephined  cases  as  those  I  have  studied 
would  be  subject  to  an  unbearable  pressure  from  without.  In  fact.  Hill's  own 
measurements  would  be  impossible,  since  what  his  tracings  show  is  how  much 
the  intracranial  pressure  is  mare  than  the  atmospheric  pressure. 

All  things  considered,  it  seems  to  me  that  a  record  of  the  brain  volume  com- 
bined with  a  tracing  of  general  arterial  pressure,  and  in  some  cases  a  venous  pulse, 
is  much  the  most  accurate  method  for  studying  the  cerebral  circulation.  To  take 
a  curve  of  intracranial  pressure  or  torcular  pressure  is  analogous  to  investigating 
the  responses  in  the  arm  by  means  of  the  pressure  in  the  axillary  vein,  adding 
the  general  arterial  and  venous  pressures  in  each  case.  Such  curves  would  be 
simply  inaccurate  criteria  of  the  amount  of  outflow, — the  more  inaccurate  the 
less  the  resistance  between  the  vena  cava  and  the  vein  recorded.  A  direct 
determination  of  inflow  or  outflow  would  be  preferable. 

The  best  worked  out  anaemia  theory  of  sleep  is  that  of  Howell.  This  investi- 
gator succeeded  in  recording  the  changes  of  volume  of  the  arm,  during  the  whole 
of  a  four  or  five  hour  period  of  sleep.  He  showed  that  the  arm  undergoes  a 
gradual  expansion  during  the  first  hour  or  more,  remains  stationary  for  some  time, 
and  then  gradually  contracts;  this  contraction  becomes  rapid  about  a  half  hour 
before  awakening.     There  are  minor  variations  in  the  curve. 

Howell  interprets  this  result  in  relation  to  the  work  of  Kohlschiitter,  Michelson 
and  others,  who  have  shown  that  the  curve  of  depth  of  sleep  falls  for  the  first 
hour  or  two,  rises  rapidly  during  the  next  half  hour,  and  then  more  slowly  during 

1  Likewise  in  those  published  in  "  Organic  Changes  and  Feeling,"  Am.  J.  of  Psy.,  1906. 


4  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

the  remaining  hours  until  awakening.  Now  we  may  suppose  that  the  cells  of 
the  cortex  are  fatigued  during  waking  hours,  and  the  vaso-motor  center  especially 
is  subject  to  fatigue,  although  it  is  kept  active  by  the  play  of  stimuli  upon  it. 
Such  fatigue  causes  a  tendency  toward  vaso-motor  relaxation,  and  withdrawal 
from  stimuli  hastens  this.  The  relaxation  affects  primarily  the  vessels  of  the 
skin  and  lowers  the  blood  pressure;  which,  according  to  the  usually  accepted 
theory  of  the  passive  condition  of  the  cerebral  vessels,  leads  to  lessened  flow 
through  the  brain,  especially  the  small  vessels  of  the  cortex;  and  this  is  the  im- 
mediate cause  of  sleep,  and  explains  its  sudden  oncoming  over  the  whole  cortex. 
The  vaso-motor  center  is  supposed  to  relax  for  an  hour  or  two,  and  then  remain 
in  this  state  for  some  time,  because  of  its  fatigued  condition.  The  cells  of  the 
cortex  regain  their  excitability  more  quickly,  hence  the  earlier  rise  of  the  curve  of 
depth  of  sleep. 

More  recently.  Brush  and  Fayerweather  have  studied  the  blood-pressure  at 
frequent  intervals  during  a  period  of  sleep.  They  find  that  the  pressure  is  always 
lowered,  and  follows  a  course  more  or  less  parallel  to  Howell's  plethysmographic 
curve.  Their  results  consequently  suggest  Howell's  explanation.  The  theory  is 
certainly  attractive,  but  we  shall  have  occasion  to  criticize  it  later. 

The  work  of  Brodmann  points  to  a  different  conclusion.  By  a  method  similar 
to  Mosso's,  he  investigated  a  person  of  rather  low  intellectual  condition,  who  had 
been  trephined  on  account  of  intracranial  pressure.  He  finds  the  brain  and  arm 
independent  of  each  other,  both  in  total  volume  and  in  undulations.  There  is 
an  increased  tendency  toward  large  fluctuations  when  the  subject  is  sleepy.  In 
going  to  sleep,  the  record  showed  an  increase  of  volume  of  the  brain,  and  usually 
of  the  arm,  an  increase  in  the  brain  pulse,  and  in  the  breathing  wave  in  the 
plethysmogram.  Subliminal  stimuli  during  sleep  give,  according  to  his  results, 
a  rise  of  volume  of  the  brain.  Quiet  awakening,  without  psychical  disturbance,  is 
accompanied  by  a  more  or  less  permanent  fall  of  volume  of  the  brain,  and  no 
permanent  change  in  the  arm  curve.  But  an  emotional -disturbance  has  more 
influence  on  the  result  than  the  process  of  awakening,  and  causes  a  vaso-dilation 
which  may  be  succeeded  by  a  constriction  in  the  brain  after  the  emotional  effect 
has  ceased. 

We  shall  find  later  that  some  of  Brodmann's  conclusions  are  probably  correct, 
but  his  curves  cannot  be  accepted  as  adequate  evidence.  Some  of  the  reactions 
are  of  doubtful  significance.  They  may  be  due  to  such  physiological  factors  as 
the  Traube-Hering  wave.  This  is  true  of  the  undulation  in  the  first  part  of 
curve  137  a. 

A  still  more  prominent  source  of  error  is  movement.  All  changes  of  position 
of  the  subject,  even  the  movements  of  breathing,  are  liable  to  influence  the  scalp. 
Anything  that  alters  the  tension  of  the  scalp  causes  violent  changes  in  the  plethys- 
mographic record,  which  have  nothing  to  do  with  the  circulation.  In  my  own 
work,  the  detection  and  elimination  of  the  effects  of  movement  were  difircult 
problems.  In  curves  as  short  as  those  of  Brodmann  there  is  still  more  chance 
of  confusion.     All  of  his  significant  tracings  are  more  or  less  ambiguous  on  this 


THE   GENERAL   PROBLEM  5 

account.  Curves  91,  IV  b,  163  and  161,  seem  to  me  entirely  obscured.  Even 
156  is  rendered  somewhat  doubtful,  although  this  is  at  least  as  good  as  any  curve 
in  the  literature. 

All  things  considered,  it  is  impossible  to  draw  any  definite  conclusion  from  the 
literature  as  to  anaemia  or  hype^^^mia  during  sleep.  Brodmann's  curves,  par- 
ticularly no.  156,  suggest  an  increased  blood  supply  to  the  brain;  and  a  critical 
study  of  Mosso's  records  does  not  conflict  with  this  result.  But  we  cannot  set 
aside  at  once  the  belief  of  Hill  that  the  cerebral  vessels  are  merely  passive ;  and 
if  this  is  true,  the  work  of  Howell  and  others  would  make  probable  a  reduced 
brain  circulation.  The  anemia  theory  is  very  plausible,  and  is  the  usual  assump^ 
tion.  Furthermore,  both  the  curves  of  Brodmann  and  those  of  Mosso  are  subject 
to  the  confusing  influence  of  movement ;  and  many  reactions  are  of  doubtful 
significance  because  of  their  small  size  or  ambiguous  relations.  Lastly,  no  pub- 
lished tracing  covers  a  long  enough  period  of  time  to  give  an  adequate  picture 
of  the  changes  that  go  with  sleep.  We  need  to  study  several  factors  in  the 
circulation  process  on  the  same  individual,  and  for  a  longer  continuous  period  of 
time;  and  the  individual  should  be  normal  in  his  general  physical  and  mental 
condition. 

General  Description  of  Method 

Two  subjects  were  used  in  the  principal  work  of  this  investigation.  The 
first  was  the  same  man  who  served  for  the  study  of  "  Organic  Changes  and 
Feeling,"  published  in  Vol.  XVH  of  the  American  Journal  of  Psychology.  He 
had  met  with  an  accident  which  necessitated  the  removal  of  a  piece  of  the  skull 
on  the  right  side  near  the  Rolandic  region.  The  area  removed  was  of  irregular 
shape,  with  diagonals  six  and  eight  cms.  in  length.  No  plate  was  used.  The 
wound  had  healed  well,  and  at  the  time  the  earlier  work  was  begun,  the  patient 
had  worked  in  Ann  Arbor  over  two  3'ears  without  inconvenience.  He  was  a 
laborer  of  at  least  average  intelligence,  and  was  normal  and  healthy.  The  hair 
was  thinner  on  the  scalp  covering  the  trephine,  and  there  was  a  considerable  dip 
or  hollow  at  that  place.  The  scalp  forming  the  floor  of  this  dip  could  be  felt 
to  pulsate. 

Experiments  on  sleep  were  carried  on  with  this  subject  during  a  part  of  two 
school  years.  Since  the  study  of  reactions  in  the  waking  state  had  preceded,  he 
was  already  thoroughly  familiar  with  the  apparatus  and  surroundings.  Con- 
sequently, it  required  only  a  few  nights  for  him  to  become  used  to  sleeping  under 
test  conditions.  He  went  to  sleep  easily,  and  his  whole  attitude  was  as  though 
he  were  taking  his  regular  rest  at  home.  The  experiments  were  usually  begun 
from  7  to  9  P.M.  and  continued  several  hours,  sometimes  all  night. 

The  second  subject  was  a  senior  student  in  the  university.  He  had  taught 
school  before  coming  here,  and  was  a  man  of  more  than  average  ability.  When 
a  child,  he  had  been  kicked  in  the  face  by  a  horse.  The  skull  had  been  broken, 
and  the  physician  had  removed  an  irregular  piece  about  2  by  4  cm.  in  area,  in  the 
right  side  of  the  forehead.     The  injury  healed  well.     At  the  time  of  the  experi- 


6  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

ments,  the  skin  was  loose  and  free  in  its  movements  over  the  trephine,  and  the 
pulsations  were  often  large. 

On  account  of  his  different  habits,  the  work  was  usually  begun  rather  later  at 
night  than  in  the  case  of  the  first  subject  It  lasted  from  two  hours  to  all  night 
(seven  hours)  according  to  circumstances.  Some  other  tests,  such  as  the  effect 
of  artificial  variations  of  breathing,  were  carried  on  either  in  the  afternoon  or  in 
the  early  part  of  the  evening.  The  experiments  were  conducted  from  one  to  three 
periods  a  week  throughout  the  greater  part  of  one  school  year  and  a  summer 
school.  At  first,  naturally,  he  found  it  difficult  to  go  to  sleep  in  the  strange  sur- 
roundings, and  knowing  that  he  was  being  studied.  But  soon  everything  became 
a  matter  of  regular  routine,  and  sometimes  it  was  difficult  for  him  to  keep  awake 
until  the  apparatus  was  ready,  except  on  one  or  two  occasions  when  he  was 
not  well. 

Other  subjects,  including  myself,  were  used  in  several  minor  experiments. 

This  investigation  includes  a  study  of  the  volume  of  the  brain  and  the  periph- 
ery (hand  or  foot),  of  the  breathing,  of  blood  pressure,  of  the  heart  rate  and 
the  time  of  transmission  of  the  pulse  wave  over  the  body,  of  the  jugular  pulse, 
and  of  the  pulse  form  and  size.  All  these  were  studied,  not  only  singly  and  during 
ordinary  sleep,  but  in  combination,  and  under  various  conditions  designed  to  show 
the  causes  of  the  reactions  found.  The  details  of  the  apparatus  and  methods, 
and  the  minor  experiments  to  test  special  points  will  be  described  under  these 
headings.  I  will  begin  with  a  general  explanation  of  the  recording  apparatus 
and  the  arrangements. 

The  kymograph  used  in  all  the  work  was  the  complete  Zimmermann  pattern, 
with  Hering  slide  and  writing  plane.  An  additional  tin  plate  was  attached  to  the 
top  of  the  metal  writing-plane.  This  made  possible  the  use  of  papers  much  wider 
than  the  drums,  and  enabled  me  to  record  several  tracings  simultaneously. 

With  the  first  subject,  the  brain  circulation  curve  was  obtained  as  follows. 
The  capsule  of  a  large  tambour  was  taken,  wide  enough  to  rest  on  the  edges  of 
bone  on  both  sides  of  the  trephine.  This  capsule  was  covered  with  thin  rubber. 
A  piece  of  cork  cut  to  fit  the  dip  over  the  trephine,  was  fastened  to  this  rubber  by 
means  of  beeswax.  A  strong  cloth  bandage  was  then  tied  firmly  around  the  head 
from  front  to  back.  From  this,  another  broad  bandage  was  passed  over  the 
trephine  to  the  opposite  side.  The  hair  was  parted  away  from  the  dip  (shaving 
the  head  was  entirely  unnecessary),  the  capsule  was  inverted  and  the  rounded 
cork  placed  in  the  cavity.  This  done,  the  broad  top  bandage  was  pulled  firmly 
but  not  too  forcefully,  down  upon  the  instrument  and  tied.  The  capsule  was  then 
connected  by  a  rubber  tube  to  a  piston  recorder.  We  shall  speak  of  this  as  the 
first  form  of  brain  plethysmograph.  Several  were  made,  in  order  that  if  one 
were  leaking,  it  could  be  replaced  without  great  delay. 

To  get  the  curve  from  the  second  subject,  two  forms  of  brain  plethysmographs 
were  used  about  equally.  One  was  like  that  designed  for  the  first  subject,  except 
that  a  circular  band  of  cork  was  fastened  to  the  edge  of  one  side  of  the  capsule. 
This  band  was  thicker  at  its  middle  than  at  its  ends,  and  served  to  make  the  instru- 


THE    GENERAL    PROBLEM  7 

ment  set  evenly  on  the  bone  around  the  trephine.  The  other  form  was  more 
analogous  to  that  used  by  Mosso  and  Brodmann.  A  plaster  of  Paris  cast  was 
made  from  the  subjects'  forehead.  On  this  a  shallow,  hard  rubber  cup  was  built, 
covering  the  position  of  the  trephine.  A  metal  tube  led  out  through  the  top  side 
of  tihe  cup,  and  a  rubber  tube  connected  this  to  a  piston  recorder.  The  edge  of  the 
cup  was  of  soft  rubber.  When  this  was  covered  with  vaseline,  and  pressed 
steadily  against  the  forehead,  it  formed  a  small,  perfectly  air-tight  chamber  over 
the  opening  in  the  skull.  We  shall  speak  of  this  as  the  second  form  of  brain 
plethysmograph.  Only  a  single  broad  bandage  tied  around  the  head  from  front 
to  back,  was  necessary  to  hold  either  form  in  place  on  the  second  subject. 

Two  breathing  tracings  were  usually  recorded,  one  from  the  chest,  the  other 
from  the  abdomen.  A  Sumner  pneumograph  connected  to  a  Marey  tambour  was 
used  for  each.  In  all  breathing  curves,  the  fall  is  due  to  inspiration,  the  rise  to 
expiration. 

It  will  be  noticed  that  all  brain  tracings  were  written  by  a  piston  recorder.  In 
fact,  all  pulse  records,  whether  from  the  brain  or  elsewhere,  were  made  by  means 
of  this  instrument.  The  form  used  was  a  modification  of  that  described  by  Lom- 
bard and  Pillsbury  in  Vol.  Ill  of  the  American  Journal  of  Physiology.  As  in 
their  work,  the  piston  was  made  of  plaster  of  Paris.  But  the  ball  and  socket 
joint  did  not  work  satisfactorily  for  me.  A  slight  inequality  in  the  weight  of 
opposite  sides  of  the  piston,  due  to  a  difference  in  absorption  of  oil,  a  particle  of 
dust  or  a  bubble  of  air  in  the  oil,  seemed  sufficient  to  cause  the  piston  to  tip  and 
bind.  It  would  often  catch  if  the  change  of  volume  moved  it  much  above  or 
below  the  level  line,  probably  because  the  oblique  position  of  the  piston  rod  pressed 
it  towards  one  side  of  the  tube.  Whenever  the  piston  began  to  tilt  for  any  reason, 
the  immediate  increase  of  friction  would  nearly  always  aggravate  rather  than 
correct  the  difficulty.  To  prevent  this,  I  cemented  the  piston-rod  firmly  into  the 
center  of  the  piston.  Under  these  circumstances  the  disk  could  be  cut  even 
thinner  than  that  used  by  Lombard  and  Pillsbury.  It  was  made  just  small  enough 
in  diameter  to  turn  almost  or  quite  over  in  the  tube  without  binding.  With  this 
arrangement  there  was  a  slightly  greater  chance  that  a  sudden  change  of  pressure 
would  force  a  bubble  of  air  past  the  piston  and  produce  an  artificial  rise  or  fall. 
But  such  an  event  seldom  occurred,  particularly  when  a  somewhat  thicker  oil  was 
used ;  and  in  any  case,  the  experienced  observer  could  easily  detect  it. 

Several  recorders  were  made,  of  different  sizes,  ranging  from  four  mm.  to 
eleven  mm.  in  the  diameter  of  the  piston.  Kerosene  was  used  with  the  smaller 
sizes  and  kerosene  mixed  with  a  thicker  oil  for  the  larger.  When  new  pistons 
are  made,  it  is  well  to  keep  them  for  a  time  in  oil. 

With  one  of  the  recorders,  I  used  a  phosphor-bronze  writing  lever  made  by 
Lombard  and  Pillsbury.  For  the  others,  I  made  levers  of  thin  celluloid.  This 
material  seems  to  me  to  meet  the  requirements  more  fully  than  the  bronze.  The 
lever  was  cut  and  bent  so  that  when  suspended  on  the  pin  used  as  axis  and 
without  the  piston-rod  attached,  it  would  balance.  When  connected  for  use, 
therefore,  the  weight  of  the  oiled  piston  and  piston-rod  tended  to  cause  the 


8  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

writing-point  to  fall.  This  prevented,  to  a  considerable  extent,  the  leakage  of  the 
oil  down  the  sides  of  the  tube,  and  also  diminished  the  extra  movement  due  to 
momentum  from  the  strong  upward  thrust  at  the  beginning  of  the  pulse-beat. 

When  the  instrument  is  set  up  for  use,  and  the  lever  is  raised  to  a  level  posi- 
tion, it  should  be  so  adjusted  that  the  piston-rod  will  lean  slightly  toward  the 
writing-point.  This  arrangement  makes  the  average  position  of  the  rod  more 
nearly  upright,  since  it  swings  away  from  the  writing-point  with  either  an  upward 
or  downward  movement. 

It  is  practically  impossible  to  prevent  a  little  oil  from  running  down  the  glass. 
This  sometimes  collects  on  the  somewhat  narrowed  bottom  of  the  barrel,  and,  on 
account  of  the  surface  tension,  acts  as  a  sort  of  plug  and  interferes  with  the  waves 
of  air  pressure  reaching  the  piston.  To  prevent  this,  a  fine  wire  was  bent  into 
the  bottom  of  the  barrel  and  served  to  lead  the  oil  down  into  the  larger  rubber 
tube  where  it  could  do  no  harm. 

In  all  the  experiments  the  subject  and  the  operator  were  in  different  rooms. 
Both  were  dark  rooms.  Ai  table  was  placed  in  the  operator's  room  near  the 
wall  between  the  two  rooms.  On  this  were  the  kymograph  and  recording 
apparatus,  the  syringes  and  attachments  used  to  regulate  the  recorders,  and  other 
apparatus  necessary  for  the  special  experiments  to  be  described  later.  On  several 
standards  nearby  were  hung  enough  smoked  papers  to  last  during  the  night's 
work.  On  the  opposite  side  of  the  wall,  in  the  sleeper's  room,  was  placed  another 
table.  The  bed  was  next  to  this.  The  bed  was  furnished  with  all  necessary 
bed-clothes,  so  that  the  subject  could  undress  and  sleep  as  usual.  There  was  a 
hole  leading  through  the  wall  between  the  two  tables.  Through  this  hole  passed 
the  tubes  connecting  the  various  plethysmographs,  pneumographs,  etc.,  to  the 
recording  apparatus.  Through  this  also  passed  the  electric  wires  for  signal  keys, 
a  large  tube  that  served  for  communication  between  an  assistant  in  the  sleeping- 
room  and  the  operator,  and  wires  for  an  electric  light  in  the  sleeping  room  so  that 
it  could  be  controlled  by  the  operator.  This  light  was  always  turned  off  while 
the  experiment  was  in  progress,  except  when  it  was  used  for  a  stimulus.  What 
space  was  left  through  the  hole  was  packed  with  cloth. 

I  was  the  operator  in  all  except  the  few  tests  in  which  I  myself  acted  as 
subject.  In  all  except  a  part  of  the  experiments  during  the  summer  school  on 
the  second  subject,  I  was  assisted  by  someone  who  understood  the  general  method 
of  work.  At  first  the  assistant  only  entered  the  bedroom  when  something  was 
wanted.  But  in  most  of  the  experiments,  he  was  seated  at  the  table,  near  the 
head  of  the  bed,  so  that  he  could  easily  reach  the  subject  to  give  stimuli,  and  could 
report  the  condition  of  the  subject  and  the  apparatus  with  the  least  possible 
disturbance.  To  enable  the  assistant  to  see  to  make  notes,  and  when  necessary, 
to  see  the  subject,  a  very  small,  shaded  electric  light  was  placed  on  his  table.  It 
was  operated  by  a  storage  battery,  and  the  circuit  was  closed  by  a  noiseless  key 
at  his  side.  This  light  was  turned  on  only  when  needed,  the  room  being  kept  in 
complete  darkness  as  much  as  possible.  Even  when  in  use,  it  was  so  located  that 
the  rays  did  not  strike  the  eyes  of  the  subject.  The  assistant  and  operator  could 
communicate  if  desirable,  by  means  of  the  large  tube  spoken  of  above. 


THE   GENERAL   PROBLEM  9 

Two  electric  indicators  wrote  on  the  drum.  One  was  controlled  by  a  key  on 
the  operator's  table,  and  was  used  by  him  to  mark  the  points  on  the  record  at 
which  notes  were  taken.  The  other  served  a  similar  purpose  for  the  assistant. 
A  thermometer  was  kept  lying  on  the  table,  and  record  was  made  of  all  significant 
changes  of  temperature.  Also  all  disturbances,  stimuli,  etc.,  were  carefully 
noted.     All  curves  are  to  be  read  from  left  to  right. 

A  careful  introspective  report  was  taken  from  the  subject  after  every  experi- 
ment, and  usually  whenever  he  awoke  during  an  experiment.  He  was  asked  to 
tell  how  he  seemed  to  have  slept ;  whether  he  remembered  anything  of  disturb- 
ances, stimuli  or  any  previous  awakenings,  and  what  he  could  recall  of  dreams. 
These  and  all  other  notes,  with  the  numbers  indicating  the  place  on  the  record 
to  which  they  referred,  were  written  on  the  back  of  the  appropriate  papers  after 
the  papers  had  been  dipped. 


CHAPTER   II 

THE  VOLUME  OF  THE  BRAIN  AND   OF  THE  PERIPHERY,  AND   THE 
BREATHING  CURVE 

Method 

It  has  been  noted  already,  that  movement  is  one  of  the  most  prominent  sources 
of  error  in  plethysmographic  work  on  the  brain.  It  obscured  many  of  the  results 
of  Brodmann  and  it  was  particularly  troublesome  in  my  work  on  the  first  subject. 
By  movement  I  mean  the  direct  action  of  contraction  of  the  voluntary  muscles  on 
the  tracing.  Even  the  interference  with  inflow  and  outflow  by  contraction  of  the 
neck  muscles  cannot  be  neglected.  But  the  most  frequent  and  most  important 
effect  is  due  to  change  in  position  of  the  scalp.  Anything  that  increases  the 
tension  of  the  scalp  over  the  trephine  will  raise  it  out  of  the  dip  and  cause  an 
apparent  increase  of  volume.  When  the  bandages  are  applied  as  they  were  with 
the  first  subject,  any  movement  that  raises  the  scalp  will  raise  the  bandages, 
lessen  the  pressure  on  the  brain  plethysmograph,  and  produce  an  apparent  fall  of 
volume.  For,  although  the  edge  of  the  plethysmograph  tambour  is  forced  against 
the  bone  around  the  trephine,  the  firmness  with  which  this  position  is  maintained 
may  vary  appreciably. 

Several  series  of  experiments  were  performed  to  show  the  effects  of  move- 
ment. In  the  first,  an  assistant  placed  his  fingers  at  the  sides  of  the  trephine,  and 
pulled  the  scalp  away  from  or  pushed  it  towards  the  opening.  In  the  second,  he 
moved  the  region  of  the  bandage  around  the  head.  In  the  third,  at  a  signal  from 
the  operator,  the  subject  raised  or  lowered  his  eyebrows,  and  moved  his  scalp 
voluntarily  in  known  ways  (so  far  as  he  could).  In  the  fourth  set,  a  control 
plethysmographic  curve  from  the  scalp  was  recorded  along  with  the  brain  tracing. 
A  second  instrument  like  that  used  over  the  trephine,  except  that  the  cork  was 
flat,  was  placed  in  an  analogous  position  under  the  same  bandage  on  the  other 
side  of  the  head.  It  was  likewise  connected  to  a  piston  recorder.  The  circulatory 
changes  in  an  area  of  the  scalp  similar  to  that  affecting  the  brain  curve,  were  thus 
recorded.  Also  any  movement  of  the  bandage  affected'  this  second  instrument 
even  more  than  that  over  the  trephine,  since  it  partly  rested  on  the  cork,  and 
the  bone  under  the  scalp  caused  every  change  of  position  to  be  fully  transmitted 
to  the  recorder.  With  the  instruments  on,  the  subject  lay  down  on  the  bed,  juid 
pulled  his  head  towards  his  body  or  pushed  it  from  his  body,  according  to  a 
signal  from  the  operator.  He  was  then  allowed  to  go  to  sleep,  and  tracings 
from  both  instruments  and  from  the  pneumographs  were  made. 

In  a  fifth  set  of  experiments,  an  additional  arrangement  was  used.  A  square 
wooden  frame  holding  a  plate  of  glass  was  taken,  and  pieces  of  rope  were  attached 


VOLUME  OF  THE  BRAIN  AND   OF  THE   PERIPHERY  u 

to  the  corners.  These  ropes  were  made  of  equal  length,  and  tied  to  another  rope 
which  dropped  from  the  ceiling.  This  gave  a  swing  which,  because  it  was 
suspended  by  a  single  cord,  could  be  moved  easily  in  any  direction.  A  pillow  was 
placed  on  the  glass  plate,  and  the  edges  of  the  frame  prevented  it  from  slipping 
off.  The  whole  was  hung  about  an  inch  from  the  head  of  the  bed,  and  at  such  a 
height,  that  when  the  body  of  the  subject  was  lying  on  the  bed,  he  could  com- 
fortably rest  his  head  on  the  pillow.  Some  tesits  were  made  in  which  the 
subject  moved  his  head  in  various  directions  while  in  this  apparatus.  Further- 
more, records  of  the  changes  during  several  hours  of  sleep  were  made,  and  the 
most  perfect  sleep  curves  from  the  first  subject  were  obtained  in  this  way.  Of 
course,  both  brain  and  scalp  tracings  were  written  in  all  these  different  kinds 
of  tests. 

The  results  of  the  various  series  of  studies  were  as  follows.  When  the 
assistant  pulled  either  scalp  or  bandage  away  from  the  opening,  the  tracing  leaped 
upward  sharply  as  expected ;  when  he  pushed  toward  the  opening,  the  tracing  fell. 
When  the  subject  raised  his  eyebrows,  the  curve  fell;  when  he  lowered  them,  the 
curve  rose.  In  the  fourth  series,  pushing  the  head  from  the  body  gave  an 
immediate  rise  in  both  records,  more  in  the  one  from  the  scalp  than  in  that  from 
the  brain;  pulling  the  head  toward  the  body  gave  a  fall  in  both  records,  more 
in  the  one  from  the  scalp.  All  these  changes  of  level  showed  an  abrupt  break 
in  the  pulse  beat  with  which  they  began,  such  as  one  would  probably  never  get 
with  true  circulation  reactions.  When  the  subject  tried  to  contract  his  muscles 
gradually,  the  break  was  much  reduced  or  absent.  But  whether  the  changes  were 
sudden  or  gradual,  they  were  not  accompanied  by  the  variations  in  the  size  and 
form  of  the  pulse,  which  usually  characterize  vaso-motor  or  blood  pressure 
responses. 

In  Fig.  I  (Plate  1)1  reproduce  a  small  extract  from  the  sleep  curves  taken 
in  the  fourth  series.  The  tracings  in  order  from  the  top  down  are :  the  abdominal 
breathing,  the  indicator  (signal)  line,  the  chest  breathing,  the  scalp  curve,  and  the 
brain  record.  Periods  of  relatively  shallow  breathing  and  considerable  snoring 
alternated  regularly  with  periods  of  deeper  breathing  and  no  snoring.  At  a 
occurred  such  a  break  in  the  breathing.  There  is  a  large  respiration  wave  in  the 
scalp  and  brain  curves.  The  fall  in  the  scalp  curve  goes  with  the  inspiration,  the 
rise  with  the  expiration.  This  is  shown  by  measurement  on  other  parts  of  the 
record  where  the  rate  of  rotation  had  been  made  faster  and  the  drum  had  been 
stopped  and  the  exact  positions  of  the  needles  marked,  so  that  the  phasic  relation 
could  be  made  out.  The  brain  curve  shows  the  same  correspondence  except  that 
often  the  rise  and  fall  begin  and  end  more  gradually  and  a  little  earlier  than  the 
same  events  in  the  scalp  curve.  The  wave  in  the  scalp  record  is  due  almost 
entirely  to  movement ;  that  in  the  brain  record  is  obviously  in  part  the  same,  but 
we  shall  find  it  is  also  in  part,  a  true  physiological  change. 

At  a,  movement  with  the  break  in  the  breathing  caused  irregularities  which  are 
partly  common  to  the  two  tracings.  In  the  brain  curve,  the  effects  of  movement 
are  compounded  with  other  changes  which  we  shall  discuss  later.     All  through  it 


12  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

will  be  seen  that  movement  does  not  influence  the  brain  record  so  much  as  that 
from  the  scalp.  At  other  times,  its  effect  was  greater  than  in  the  part  reproduced. 
At  still  other  times,  when  the  instruments  were  tied  on  more  firmly,  the  effect 
was  decreased,  the  brain  pulse  was  larger  and  apparently  more  perfect.  In  any 
case,  the  factor  of  movement  must  be  reckoned  with,  and  its  elimination  is  often 
difficult. 

In  the  fifth  series  this  elimination  was  practically  accomplished.  Quick  move- 
ments by  the  subject  caused  a  temporary  disturbance  of  the  record;  slow  move- 
ments gave  nothing.  Portions  of  the  sleep  curves  taken  under  the  conditions  of 
this  experiment  will  be  reproduced  later.  It  will  then  be  seen  that  the  effects 
of  movement  are  at  least  reduced  to  a  minimum. 

For  some  of  the  experiments  on  sleep,  the  apparatus  was  still  further  com- 
plicated. A  second  kymograph  was  placed  horizontally  a  little  below  the  level  of 
the  swing  and  on  that  side  of  it  opposite  to  the  bed.  The  axis  of  the  drum  was 
perpendicular  to  the  edge  of  the  swing.  A  flexible  needle  was  attached  to  the 
swing  so  that  it  would  write  on  the  drum.  In  this  way  a  record  was  obtained  of 
the  movements  of  the  swing.  It  was  found  that  in  sleep  the  subject  draws  his 
head  towards  his  body  during  inspiration,  and  pushes  it  from  his  body  during 
expiration.  The  usual  movement  was  about  four  mm.  This  accounts  for  the 
large  respiratory  wave  in  the  scalp  and  brain  records  when  the  swing  was  not 
used.  Such  a  peculiar  movement  in  its  various  relations  would  probably  repay 
more  study  than  I  have  given  it. 

Tests  carried  out  on  the  second  subject  showed  that  movement  played  a  less 
important  part  than  in  the  case  of  the  first  subject  It  was  necessary  to  use  the 
swing  to  eliminate  it  when  he  was  lying  on  his  side  or  on  his  face.  But  when  he 
was  lying  on  his  back,  its  influence  was  seldom  marked,  because  of  the  position 
of  the  trephine,  no  doubt. 

The  curves  taken  from  the  scalp  as  described  above  show  also  that  the  circula- 
tion in  the  scalp,  although  it  gives  a  tracing,  is  negligible  so  far  as  its  influence 
on  the  brain  record  is  concerned. 

The  peripheral  volume  recorded  was  either  from  the  foot  or  from  the  hand. 
The  principle  of  the  Hallion-Comte  plethysmograph  was  used.  But  I  found  that 
camera  bulbs,  of  a  size  and  weight  which  experience  had  shown  to  be  adapted  to 
the  work,  gave  better  results  than  bulbs  usually  made  for  the  purpose.  Two  or 
three  fingers  and  sometimes  the  thumb  served  for  a  hand  curve.  For  the  foot, 
the  bulb  was  applied  at  the  side  just  above  the  heel.  Such  an  arrangement  may 
be  influenced  by  movements  whenever  the  subject  is  disturbed.  And  it  does  not 
include  all  of  any  part  of  the  body,  so  that  some  of  the  record  desired  is  lost. 
Other  plethysmographs  get  rid  of  these  troubles  with  greater  or  less  success.  The 
finger-plethysmograph,  when  properly  suspended,  is  the  most  perfect  form,  and 
was  used  in  a  few  experiments.  But  it  is  inconvenient  in  work  on  sleep,  and 
others  are  worse.  They  are  a  continual  source  of  disturbance  to  the  subject.  The 
bulb  gave  a  fairly  true  tracing  except  when  movement  came  in,  and  such  places 
can,  in  general,  be  easily  detected.     The  complete  continuity  of  the  peripheral 


VOLUME  OF  THE  BRAIN  AND  OF  THE  PERIPHERY        13 

record  was  often  lost,  but  this  was  less  important  than  the  convenience  of  the 
subject  which  made  possible  a  perfect  brain  curve.  So  the  bulb  arrangement 
w^as  used. 

The  pistons  of  the  recorders  used  in  writing  the  curves  were  of  three  .sizes, 
8.1  mm.,  6.5  mm.,  and  4.6  mm.  in  diameter.  The  distance  from  the  axis  to  the 
tip  of  the  needle  used  with  the  large  piston  was  12.3  cm. ;  the  distance  from  the 
axis  to  the  point  of  attachment  of  the  piston-rod  on  the  same  needle  was  2.3  cm. 
One  of  the  medium  pistons  was  connected  to  a  needle  on  which  the  distance 
from  the  axis  to  the  tip  was  8.7  cm.,  the  distance  from  the  axis  to  the  insertion 
of  the  piston-rod  was  1.25  cm.  The  other  medium  pistons  were  used  with 
needles  on  which  the  first  measurement  was  10  cm.,  the  second  was  2  cm.  The 
actual  movement  of  the  piston  of  the  large  recorder  would,  therefore,  be  given 
approximately  by  dividing  the  movement  of  the  writing-point  by  5.3.  The  same 
value  for  the  first  of  the  medium  recorders  would  be  given  by  dividing  the 
movement  of  the  point  by  7 ;  and  the  divisor  for  the  other  recorders  would  be  5. 
These  facts  will  be  made  use  of  to  express  the  actual  change  of  volume  recorded 
by  the  instruments. 

Results  with  the  Subject  Lying  on  his  Back 

The  volume  was  studied  during  the  waking  condition  before  sleep,  in  going 
to  sleep  and  during  sleep,  at  awakening  and  after  awakening.  This  was  done 
while  the  subject  was  lying  on  his  back;  wllien  he  was  lying  in  other  positions; 
when  he  was  sitting  propped  up  in  such  a  way  that  his  legs  and  hips  rested  on 
the  bed,  while  his  body  leaned  against  a  support  covered  with  bedding,  and 
inclined  at  an  angle  of  about  fifty  degrees  with  the  plane  of  the  bed;  and  when 
he  was  sitting  up  leaning  forward  against  a  support.  Studies  were  also  made 
on  the  influence  of  interference  with  the  jugulars  and  with  the  carotids;  on  reac- 
tions to  stimuli  when  awake;  on  the  effect  of  artificial  variations  of  breathing; 
and  on  the  curve  of  drowsiness  when  the  subject  was  sitting  up  and  wben  he 
was  lying  down.  These  topics  will  be  taken  up  in  order.  I  shall  turn  now  to  a 
description  of  a  few  typical  records  taken  when  the  subject  was  lying  on  his  back. 
Illustrations  taken  from  different  parts  of  a  single  period  of  work  are  in  some 
ways  of  more  value  than  those  selected  promiscuously  from  various  times.  I 
begin  with  a  series  of  extracts  from  the  work  of  February  20,  1906,  on  the  first 
subject,  J. 

/.,  February  20, 1,  no.  i  (Fig.  2,  Plate  2). — This  record  commenced  soon  after 
the  lights  in  the  sleeping  room  were  turned  out,  and  while  the  subject  was  still 
awake.  The  curves  in  order  from  the  top  down  are  the  abdominal  breathing,  the 
indicator  line,  the  chest  breathing,  the  tracing  from  the  scalp,  and  that  from  the 
brain.  This  arrangement  will  be  found  in  all  the  extracts  from  February  20, 
1906.  Also  in  all  records  from  that  date,  the  brain  volume  was  written  by  the 
large  piston  recorder,  in  which  the  piston  was  8.1  mm.  in  diameter,  and  the  move- 
ment of  the  writing  point  equaled  the  movement  of  the  piston  multiplied  by  5.3. 


14  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

The  scalp  record  was  written  by  the  first  medium  recorder,  in  which  the  index 
of  magnification  was  7.  The  complete  apparatus  for  detection  and  elimination 
of  movement  was  used. 

The  subject  was  awake,  although  sleepy  at  the  start.  He  went  to  sleep 
gradually,  and  was  asleep  at  the  end  of  this  extract.  At  a  the  drum  was  stopped 
an  instant  to  give  lines  of  reference  for  a  comparison  of  the  curves,  b-c  repre- 
sents the  level  line  of  the  brain  recorder,  to  which,  by  taking  account  of  the  move- 
ment of  the  needle  in  an  arc,  all  points  of  the  curve  may  be  reduced  for  accurate 
measurement.  The  temperature  was  falling  in  the  bedroom,  which  caused  a 
contraction  of  the  air  in  the  tubes  and  a  gradual  fall  of  the  scalp  tracing.  In 
spite  of  this,  however,  the  brain  curve  rose  between  two  and  three  centimeters 
as  the  subject  went  to  sleep.  The  size  of  the  brain  pulse  did  not  change  greatly; 
on  the  average  it  was  perhaps  slightly  increased.  Under  d,  the  scalp  record  was 
raised  artificially;  under  e,  the  brain  record  was  lowered  to  prevent  their  inter- 
ference with  each  other. 

A  marked  breathing  wave  was  coming  into  the  brain  curve,  as  the  subject 
began  to  sleep  soundly  near  the  end  of  the  selection.  This  could  not  be  due  to 
movement,  since  the  scalp  tracing  shows  that  movement  was  eliminated  by  use 
of  the  swing  (compare  Fig.  i  and  discussion  of  movement).  There  was  some 
evidence  of  the  breathing  wave  in  the  early  part  of  the  record,  when  the  subject 
was  awake,  but  it  became  much  greater  as  the  subject  went  to  sleep  and  the 
volume  rose.     It  is  shown  in  the  scalp  record  mainly  by  change  in  size  of  the  pulse. 

It  will  be  seen  also  that  there  was  a  noticeable,  longer  fluctuation  in  the 
volume  of  both  brain  and  scalp  at  the  beginning  of  the  curves.  This  is  usually 
called  the  Traube-Hering  or  Sigmund  Mayer  wave.  As  the  subject  went  to  sleep, 
it  became  much  more  prominent,  particularly  in  the  brain.  Measurement  from 
the  lines  of  reference  at  a  shows  that  these  waves  were  very  nearly,  if  not  quite, 
parallel  in  time  of  occurrence  in  the  two  curves ;  but  the  variations  in  size  were  by 
no  means  parallel  in  the  two. 

The  breathing  changes  as  sleep  came  on  were  characteristic.  The  abdominal 
tracing  was  much  reduced.  In  both  chest  and  abdomen  there  appeared  a  some- 
what irregular  alternation  of  shallower  breathing,  accompanied  by  more  or  less 
snoring,  and  deeper  breathing  accompanied  by  a  break  in  the  snoring.  Measure- 
ment from  a  shows  that,  in  general,  the  decreased  breathing  corresponds  to  a  rise 
in  volume,  the  increased  breathing  to  a  fall  in  volume.  The  increase  in  breathing 
often  begins  a  little  before  the  decrease  in  volume.  These  relations  are  not  so 
obvious  in  the  minor,  shorter  waves  as  in  the  larger  ones.  So  we  see  the  Traube- 
Hering  wave  of  the  waking  condition  gradually  changed  into  a  wave  with  accom- 
panying respiratory  changes  in  sleep.  It  should  be  remarked  that  the  shallow 
breathing  was  not  always  accompanied  by  noticeable  snoring.  Snoring  is  shown 
in  the  tracing  by  the  check  and  irregularity  in  the  inspiratory  fall  of  the  chest 
curve. 

There  were  significant  changes  in  pulse  form  in  this  and  the  other  records,  but 
these  will  be  discussed  later. 


VOLUME  OF  THE  BRAIN  AND  OF  THE  PERIPHERY        15 

/.,  February  20,  I,  no.  2  (Fig.  3,  Plate  i). — This  was  a  later  portion  of  the 
same  record.  Its  diameter  was  reduced  one  half  in  the  reproduction.  It  began 
with  a  period  of  decreased  breathing  and  snoring.  Corresponding  to  this,  the 
brain  volume  was  rising;  throughout  the  preceding  part  of  the  record,  the  brain 
showed  a  large  fluctuation  corresponding  to  the  variations  of  breathing,  and  this 
rise  was  a  section  of  such  a  fluctuation.  The  breathing  wave  in  the  brain  and 
scalp  curves  was  even  greater  than  in  the  first  extract,  and,  although  the  scalp 
record  shows  that  this  might  be  slightly  due  to  movement,  such  effect  of  move- 
ment was  negligible.  A  period  of  increased  and  free  breathing  accompanied  by 
a  fall  of  brain  volume  followed.  This,  in  turn,  was  followed  by  three  restricted 
breaths  and  the  beginning  of  a  rise  in  volume.  Then  the  subject  was  touched 
lightly  by  the  assistant.  The  mark  indicating  the  touch  was  a  little  late,  since 
the  assistant  had  to  return  to  his  seat  to  press  the  key  after  giving  the  stimulus. 
The  result  was  increased  and  free  breathing  in  both  chest  and  abdomen,  and  a 
marked  fall  in  the  volume  of  the  brain.  The  breathing  change  began  at  very 
nearly  the  same  time  as  the  volume  change.  Then  followed  a  period  of  decreased 
breathing  and  rising  volume  until  near  the  end  of  the  section.  A  temporary  break 
in  breathing  accompanied  by  a  short  decrease  of  volume  was  followed  by  restricted 
breathing  and  rising  brain  curve  at  the  end.  It  will  be  noticed  that  the  breathing 
wave  in  the  brain  very  nearly  disappeared  with  the  free  breathing  and  fall  of 
volume,  and  reappeared  with  the  rising  curve.  It  varied  analogously  in  the  scalp 
curve.  The  regularity  of  the  scalp  tracing  shows  that  it  is  impossible  to  explain 
any  of  these  changes  by  movement,  and  they  must  represent  reactions  in  the 
cerebral  circulation. 

].,  February  20,  II,  no.  i  (Fig.  4,  Plate  3). — More  than  half  an  hour  had 
elapsed  since  the  taking  of  I,  no.  2.  Four  stimuli,  which  disturbed  the  subject 
slightly  but  did  not  awake  him,  had  been  given.  All  resulted  in  a  similar  fall  of 
volume.  Two  of  these  falls  were  of  much  longer  duration  than  that  published 
in  the  preceding  extract,  and  required  three  or  four  times  as  long  a  recovery 
period. 

This  section  is  selected  as  representing  in  its  extreme  form  another  type  of  the 
effects  of  disturbance,  a-b  marks  the  level  line  of  the  brain  recorder.  The  trough 
of  a  Traube-Hering  wave  occurred  just  at  the  beginning,  and  following  this,  the 
breathing  was  restricted  and  the  volume  rose.  The  brain  record  was  so  high 
that  the  brain  and  scalp  curves  interfered  with  each  other;  although,  on  account 
of  its  movement  in  an  arc,  the  brain-recorder  lever  was  writing  in  front  of  the 
other.  Just  before  the  mark  c,  the  subject's  foot,  which  had  been  resting  on  the 
edge  of  the  bed,  slipped  off.  There  was  no  other  disturbance,  and  the  assistant 
reported  that  the  subject,  except  for  the  temporary  change  of  breathing,  con- 
tinued to  sleep.  There  were  two  deep  inspiratory  movements  followed  by  lighter 
and  freer  breathing  for  several  breaths.  The  rate  of  breathing  was  increased. 
The  brain  curve  rose,  or  rather  was  held  up  to  what  had  been  the  highest  crest 
of  the  breathing  waves  for  about  six  pulse  beats;  the  pulse  was  at  this  point 
much  restricted.     The  volume  then  fell  to  a  much  lower  level,  with  a  pulse  as 


1 6  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

large  or  larger  than  it  had  been  before  the  disturbance.  Over  e  is  a  change, 
probably  to  be  correlated  with  the  aheck  in  breathing  at  the  same  point,  but  we 
do  not  know  just  how.  The  scalp  curve  fell  somewhat,  and  was  raised  artificially 
at  d ;  and  its  irregularities  show  that  there  was  some  movement.  This  movement 
may  have  caused  slight  irregularities  in  the  brain  pulse  record  but  was  negligible 
in  comparison  with  the  change  in  the  cerebral  circulation.  The  restricted  breath- 
ing and  snoring  soon  returned  and  with  it  the  rise  in  volume  of  the  brain.  The 
respiration  wave  in  the  volume,  which  disappeared  during  the  disturbance,  came 
back  with  the  rising  volume. 

/.,  February  20,  III,  no.  i  (Fig.  5,  Plates  4  and  5)^ — This  began  about  fifteen 
minutes  after  the  preceding  extract.  The  subject  had  moved  his  head  slightly 
once,  but  there  had  been  no  other  disturbance,  and  he  had  slept  continuously 
except  for  the  alternation  of  restricted  breathing  and  rise  of  volume  with  freer 
breathing  and  fall  of  volume.  Such  alternation  of  breathing  and  volume  changes 
is  shown  characteristically  in  the  first  part  of  the  extract.  Or-h  is  the  level  line 
of  the  brain  recorder,  c,  d,  e  and  /  designate  breaks  in  the  breathing  and  the 
accompanying  fall  of  volume.  At  4  the  subject  also  moved  his  head  slightly, 
which  gave  a  somewhat  greater  fall  of  volume.  The  phasic  relation  of  the  breath- 
ing and  volume  changes  can  be  more  clearly  made  out  from  records  which  were 
taken  to  study  the  pulse-rate  and  transmission  time,  and  which  will  be  discussed 
later.  But  it  can  be  determined  with  a  reasonable  degree  of  accuracy  from  the 
curves  now  being  considered.  At  g  and  again  at  the  end  of  the  section,  the 
drum  was  stopped  for  a  moment  to  allow  the  needles  to  write  lines  that  would 
denote  their  relative  positions.  Then  by  a  method  to  be  described  in  more  detail 
later,  points  in  the  brain  tracing  were  reduced  to  corresponding  points  on  the 
level  of  a-b ;  and  a  celluloid  square,  one  edge  of  which  moved  along  the  indicator 
line,  was  used  to  compare  the  breathing  curve  with  these  reduced  points.  It  was 
found  that  the  beginning  of  freer  breathing  is  almost  simultaneous  with  the 
suppression  of  the  breathing  wave  in  the  volume,  or  may  occur  a  couple  of  pulse 
beats  before  the  change  in  the  brain;  but  the  brain  curve  is  usually  held  high 
from  four  to  eight  pulse-beats  longer  before  the  real  fall  of  volume  begins.  The 
size  of  the  pulse  at  this  high  position  is  often  less  than  at  a  similar  level  of  volume 
during  a  period  of  restricted  breathing. 

The  scalp  tracing  shows  that  movement  had  some  effect  at  times  in  spite  of  the 
swing.  (On  account  of  the  faintness  of  the  tracing,  the  first  part  of  this  curve 
did  not  reproduce  well.)  Similar  effects  of  small  degree  can  in  some  cases  be 
made  out  in  the  brain  curve,  but  they  are  too  small  and  temporary  to  be  of 
importance. 

This  record  shows  how  large  the  breathing  wave  in  the  volume  may  become 
during  the  periods  of  restricted  breathing  and  snoring.  The  restricted  respiration 
is  also  the  slower;  the  freer  is  the  more  rapid. 

At  5  the  assistant  started  to  awaken  the  subject.  There  was  very  little  move- 
ment and  practically  no  disturbance  of  the  curves  by  movement.     During  awaken- 

1  On  account  of  the  length  of  this  record,  it  was  necessary  to  reproduce  it  in  two  parts. 


VOLUME  OF  THE  BRAIN  AND  OF  THE  PERIPHERY        i? 

ing  the  amplitude  of  breathing  was  much  increased  in  both  chest  and  abdomen. 
Later,  when  the  subject  was  more  completely  awake,  the  amplitude  of  the  chesf 
movements  became  reduced  again,  the  abdominal  movements  remained  large. 
Since  the  rotation  of  the  kymograph  is  probably  approximately  constant,  the 
change  in  rate  of  breathing  can  be  expressed  with  some  accuracy  in  terms  of  the 
average  length  of  breath  in  centimeters.  We  find  that  during  the  periods  of 
restricted  breathing  in  sleep,  the  breaths  averaged  0.58  cm.  in  length  ;  with  periods 
of  freer  breathing  in  sleep,  the  length  averaged  0.5  cm. ;  at  awakening,  the 
average  length  was  0.45  cm.;  when  the  subject  was  more  completely  awake,  it 
was  0.47  cm.  The  rate  of  respiration  was  therefore  increased  more  at  awakening 
than  at  periods  of  freer  breathing  in  sleep,  and  persisted  more  than  the  increase 
in  amplitude  in  the  chest. 

With  awakening,  the  volume  of  the  brain  was  decreased  to  a  point  less  than 
at  any  time  during  sleep,  and  it  remained  low  as  long  as  the  subject  was  awake. 
The  size  of  the  pulse  was  likewise  lessened.  There  was  still  a  respiration  wave 
in  the  brain,  but  it  was  very  small  compared  with  that  in  sleep.  The  breathing 
wave  also  disappeared  from  the  scalp  tracing.  Just  as  the  assistant  started  to 
awaken  the  subject,  a  rise  in  volume  with  restricted  breathing  was  beginning.  It 
was  checked  by  the  awakening,  but  perhaps  the  trough  under  h  corresponds 
approximately  to  what  would  have  been  the  position  of  the  next  fall  with  freer 
breathing.  At  any  rate,  the  fluctuation  of  volume  with  accompanying  breathing 
changes  of  sleep,  was  succeeded  by  a  much  smaller  Traube-Hering  wave  in  the 
waking  condition. 

When  the  subject  was  awake,  the  lights  were  again  turned  out  and  he  was 
allowed  to  go  to  sleep  once  more.  This  he  did  gradually,  and  was  sleeping  fairly 
well  at  the  end  of  the  record.  The  temperature  of  the  rooms  was  falling,  so  that 
the  scalp  tracing  sank  slowly  and  was  raised  artificially  once.  In  spite  of  this 
falling  temperature,  the  brain  volume  increased  regularly  and  constantly.  The 
size  of  the  pulse  also  became  greater.  The  changes  in  cerebral  volume  and  size 
of  pulse  were  so  marked,  regular  and  sustained,  that  this  record  shows  almost 
perfectly  the  whole  process  of  awakening  and  going  to  sleep  again.  In  the  course 
of  a  few  minutes,  the  abdominal  breathing  curve  became  of  less  amplitude,  and 
then  periods  of  still  more  reduced  abdominal  breathing  and  irregular  and  restricted 
chest  breathing  began  to  be  succeeded  by  freer  and  larger  breathing  movements  in 
each.  Corresponding  to  this,  the  Traube-Hering  wave  in  the  brain  gradually 
became  the  fluctuation  of  volume  with  periodic  change  of  breathing.  At  first 
in  this  fluctuation,  the  increase  in  breathing  sometimes  seemed  to  precede  the 
beginning  of  the  fall  of  volume;  sometimes  the  fall  of  volume  seemed  to  begin 
before  the  increase  in  breathing;  but  it  is  difficult  to  be  entirely  certain  of  the 
exact  relation.  The  large  breathing  wave  in  the  volume  returned  as  sleep 
came  on. 

J.,  February  20,  IV,  no.  i  (Fig.  6,  Plate  6). — This  record  is  reproduced  in 
order  to  show  the  phasic  relation  between  the  breathing  curve  and  the  breathing 
wave  in  the  brain  curve.     The  rate  of  rotation  of  the  drum  was  increased  so  that 


i8  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

it  would  show  the  details  of  pulse  form  and  the  interrelation  of  the  tracings. 
At  a  the  kymograph  was  suddenly  stopped,  and  the  needle  allowed  to  describe  arcs 
of  reference.  The  rate-control  was  changed  to  its  original  condition  and  the 
drum  suddenly  started  again.  The  subject  was  sleeping  soundly.  It  will  be  seen 
that  the  breathing  wave  with  the  slow  rate  was  much  like  that  in  the  preceding 
curves.  Measuring  back  from  the  arcs  of  reference,  it  is  found  that  the  begin- 
ning of  the  rise  from  the  trough  of  volume  b  occurs  a  little  more  than  half  way 
down  the  fall  corresponding  to  inspiration  in  the  chest  breathing  curve.  The 
beginning  of  the  fall  from  the  crest  c  is  on  the  expiratory  rise  in  the  breathing 
tracing,  and  about  one-fourth  the  distance  from  the  top.  The  troughs  d  and  / 
correspond  to  points  somewhat  more  than  two-thirds  the  distance  down  the 
inspiratory  falls.  And  the  fall  from  the  crest  e  begins  about  one-fourth  the 
distance  from  the  top  of  the  expiration.  . 

The  beginning  of  each  pulse-beat  in  the  scalp  curve  was  carefully  marked 
under  a  magnifying  glass.  A  celluloid  straight-edge  was  laid  along  the  record 
and  the  troughs  marked  by  an  L.  It  will  be  seen  that  the  breathing-wave  in  the 
scalp  is  considerably  delayed  beyond  the  corresponding  brain  record,  even  beyond 
the  turning  points  in  the  breathing. 

J.,  February  20,  IV,  no.  2  (Fig.  7,  Plate  7). — Only  a  short  space  is  omitted 
between  no.  i  and  this.  The  record  shows  the  same  fluctuations  of  breathing  and 
volume  that  were  found  in  the  previous  charts.  As  before,  the  beginning  of  freer 
breathing  nearly  coincides  with  the  cessation  of  the  large  respiratory  wave  in 
the  brain,  but  the  brain  volume  remains  level  or  even  increases  several  pulse-beats 
before  the  fall  begins.  It  will  be  noticed  that  during  the  periods  of  restricted 
breathing  the  inspirations  are  greater  than  the  expirations,  so  that  the  subject 
holds  himself  more  and  more  in  the  condition  of  inspiration;  with  the  freer 
breathing,  the  subject  quickly  returns  to  normal.  These  statements  are  not  true 
of  all  such  fluctuations,  but  they  are  true  of  a  considerable  part.  The  period  of 
free  breathing  at  a  is  quickly  succeeded  by  rather  irregular  and  restricted  breath- 
ing. The  brain  volume  rises  to  a  high  level  at  first,  and  shows  comparatively 
little  fall  afterwards.  Possibly  one  might  interpret  such  a  case  as  a  simple 
tendency  toward  increase  of  volume,  if  comparison  with  the  usual  waves  did  not 
show  that  it  is  merely  an  abbreviated  reaction. 

At  4  the  assistant  started  to  awaken  the  subject.  There  was  the  usual  increase 
in  depth  of  both  chest  and  abdominal  breathing,  followed  by  a  decrease  in  the 
chest  when  he  was  more  nearly  awake.  The  average  length  of  respiration  was 
0.7  cm.  during  restricted  breathing,  0.48  cm.  during  the  increased  breathing  at 
awakening,  and  0.5  cm.  afterwards.  As  before,  there  was  a  decrease  in  the  brain 
volume  and  to  some  extent  in  the  size  of  pulse.  The  respiratory  wave  was  almost 
eliminated,  and  the  Traube-Hering  wave  became  very  small.  The  scalp  tracing 
shows  that  at  h  there  were  two  temporary  effects  of  movement  of  considerable 
size,  but  they  had  proportionally  small  influence  on  the  brain  record. 

When  the  drum  was  stopped,  the  subject  said  he  remembered  of  being 
awakened  before,  but  remembered  nothing  else  since  he  went  to  sleep. 


VOLUME  OF  THE  BRAIN  AND  OF  THE  PERIPHERY        ip 

November  14,  III  (Fig.  8,  Plate  8). — This  is  an  extract  from  a  record  taken 
before  the  swing  was  constructed.  It  is  therefore  subject  to  the  cfifects  of  move- 
ment. The  brain  curve  is  at  the  bottom,  and  comparison  with  the  charts  we  have 
already  discussed  shows  that  a  considerable  part  of  its  respiratory  wave  was 
probably  due  to  movement.  It  was  written  with  a  large  recorder.  The  hand 
tracing  is  next  above.  It  will  be  seen  that  the  band  volume  also  showed  a  con- 
siderable respiratory  wave.  The  chest  breathing  curve  is  just  below  the  indicator 
line  (the  abdominal  is  not  recorded).  At  a  the  light  was  turned  on,  and  at  b 
the  assistant  disturbed  him.  Before  the  stimulus,  the  breathing  had  been  deep 
and  regular  without  definite  snoring.  With  the  stimulus,  it  became  much 
shallower;  but  the  change  was  not  sudden  as  in  February  20;  the  depth  gradually 
became  less  and  then  greater  again.  The  rate  of  respiration  was  increased 
temporarily.  There  was  a  fall  in  the  volume  of  the  hand,  which  continued 
throughout  the  selection,  and  the  needle  had  to  be  raised  twice  artificially.  The 
respiratory  wave  in  the  hand  was  much  diminished.  The  influence  of  movement 
is  obvious  in  the  brain  curve,  but  it  shows  a  definite  fall,  which  began  to  recover 
earlier  than  the  hand. 

In  other  parts  of  the  same  record  from  which  this  extract  was  taken,  there 
are  two  additional  and  similar  reactions  to  a  stimulus.  There  is  also  a  rather 
irregularly  periodic  decrease  and  increase  of  breathing  of  like  kind  occurring 
without  stimuli,  except  that  shallow  breathing  is  usually  not  also  faster,  may  even 
be  slower,  and  in  all  these  cases,  the  decrease  of  breathing  corresponds  to  the 
rising  volume,  the  increase  to  the  falling  volume.  In  some  places  this  correspond- 
ence is  not  exact,  though  it  is  usually  quite  close. 

Fig.  I  (Plate  i). — This  has  already  been  described.  It  remains  only  to  call 
attention  to  the  fact  that  accompanying  the  increase  in  depth  and  rate  of  breathing, 
the  brain  volume  remained  about  stationary  with  cessation  of  the  respiratory 
wave  for  a  few  pulse-beats,  and  then  fell  to  a  distinctly  lower  level.  It  began 
to  recover  soon  afterwards. 

H.,  April  6,  I  (Fig.  9,  Plates  9  and  lo)^  (April  6,  1907). — This  record  from 
the  second  subject  commenced  soon  after  the  lights  in  the  bed-room  were  turned 
out,  and  while  he  was  still  awake.  The  top  curve  is  that  of  abdominal  breathing, 
and  just  below  that  is  the  chest  breathing.  Then  follow  an  indicator  line  used  by 
the  operator,  one  used  by  the  assistant  in  the  bed-room,  and  the  brain  record. 
The  brain  volume  was  written  by  a  medium-sized  recorder,  in  which  the  piston 
was  6.5  mm.  in  diameter,  and  the  ratio  of  the  movement  of  the  piston  to  move- 
ment of  the  writing-point  was  i  to  7.  The  first  form  of  brain  plethysmograph 
was  used  on  the  head.  Since  tests  had  shown  that  movement  seldom  influenced 
the  curve  from  this  subject  appreciably  w^hen  he  was  lying  on  his  back,  no  appa- 
ratus for  elimination  of  movement  was  necessary.  Or-b  is  the  level  line  of  the 
recorder.     The  temperature  in  the  sleeping-room  was  falling  a  little. 

The  subject  was  awake  at  the  start.  He  went  to  sleep  in  a  manner  char- 
acteristic of  him  and  often  found  in  all  subjects.     Periodic  decrease  and  increase 

2  On  account  of  the  length  of  this  record,  it  was  necessary  to  reproduce  it  in  two  parts. 


20  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

of  breathing  was  accompanied  by  increase  and  decrease  of  brain  volume.  This 
periodic  change  showed  equally  in  chest  and  abdomen.  The  decrease  in  breathing 
usually  came  on  gradually,  the  increase  was  more  sudden.  The  restriction  of 
breathing  during  the  low  ebb  of  each  period  was  very  marked,  particularly  at 
first.  Measurement,  after  reducing  the  brain  tracing  to  its  level,  shows  that 
the  increase  in  breathing  begins  as  a  rule  somewhat  before  the  fall  of  volume. 
The  fall  in  volume  was  generally  much  more  abrupt  than  the  rise.  Under  c  and 
d  the  brain  curve  was  lowered  artificially,  3  cm.  or  more  in  each  case,  to  keep  the 
recorder  within  the  range  in  which  it  would  work  most  freely.  Finally  the  last 
restriction  of  breathing  was  less  extreme  and  changed  gradually  into  an  amplitude 
of  both  chest  and  abdominal  movement  rather  greater  than  during  the  waking 
condition.  The  assistant  reported  that  at  i  the  subject  jerked  a  little,  at  2  he  was 
beginning  to  snore,  at  5  he  had  stopped  snoring,  and  at  4  he  was  snoring  regularly. 
This  snoring  was  distinct  but  not  particularly  labored.  The  inspiratory  fall  of  the 
chest  breathing  shows  the  check  clearly. 

Counting  the  artificial  drops  at  c  and  d,  it  will  be  seen  that  the  brain  volume 
rose  about  6  cm.  as  the  subject  went  to  sleep,  and  this  in  spite  of  a  falling 
temperature.  The  size  of  the  arterial  pulse  from  the  brain  was  also  greatly 
increased,  about  doubled. 

The  breathing-wave  which  came  into  the  curve  as  the  subject  began  to  sleep 
regularly  was  large,  although  not  quite  so  marked  as  with  the  first  subject.  The 
pulse  was  of  distinctly  smaller  size  at  the  trough  than  at  the  crest.  Towards  the 
end  of  this  extract,  the  kymograph  was  run  more  rapidly.  Measurement  from  the 
lines  of  reference  would  show  with  great  accuracy  the  phasic  relation  of  the 
two  breathing  waves  in  this  portion  of  the  record,  and  with  fair  accuracy  the 
relation  in  the  preceding  portion.  It  was  found  in  this  way  that  the  trough  of  the 
volume  wave  occurred  on  or  just  at  the  beginning  of  the  check  in  the  inspiratory 
fall;  the  crest  in  the  volume  wave  occurred  on  the  latter  half  of  the  expiratory 
rise,  usually  near  its  end. 

The  real  waking  condition  did  not  last  long  enough  to  study  the  Traube-Hering 
wave  in  it.  But  the  large  fluctuation  in  volume,  with  accompanying  changes  in 
depth  of  breathing  characteristic  of  going  to  sleep,  became  a  shallower  Traube- 
Hering  wave  of  similar  limits  of  length  during  sleep.  There  does  not  seem  to 
be  any  regular  change  in  depth  of  breathing,  corresponding  to  this  Traube-Hering 
wave.  A  thin  piece  of  celluloid,  on  which  lines  were  ruled  i  mm.  apart,  was  laid 
along  the  respiratory  curve,  and  the  variations  in  depth  of  breathing  were  care- 
fully measured.  There  was  some  indication  that  a  slightly  reduced  respiration 
occurs  in  a  trough  or  on  a  rise  of  volume,  but  no  relation  could  be  determined 
with  certainty. 

H.,  April  6,  II,  no.  i  (Fig.  id,  Plate  11). — This  portion  was  taken  about 
twenty-five  minutes  after  the  preceding  one.  The  drums  had  been  stopped  once 
to  change  papers,  during  which  time  the  subject  slept  evenly.  Otherwise  a  con- 
tinuous record  had  been  taken.  Approximately  five  minutes  before,  the  subject 
had  ceased  snoring,  and  awakened  sufficiently  to  change  his  position,  although 


VOLUME  OF  THE  BRAIN  AND  OF  THE  PERIPHERY        21 

not  sufficiently  to  recognize  stimuli.  The  disturbance  was  accompanied  by  a 
decrease  of  volume  and  size  of  pulse.  This  chart  begins  where  the  movements 
ceased,  and  the  subject  was  going  to  sleep  again.  At  5  the  assistant  noted  that  he 
was  beginning  to  snore.  Sleep  brought  with  it  a  rise  of  volume,  and  increase  in 
the  size  of  pulse.  The  respiratory  wave  in  the  brain  returned,  and  the  Traube- 
Hering  wave  seems  to  be  continuous  from  low-volume  to  high-volume.  The 
changes  in  depth  of  breathing  accompanying  the  fluctuations  of  volume  were 
small,  and  measurement  from  lines  of  reference  in  the  tracings  just  after  the  part 
reproduced,  shows  that  the  increase  in  breathing  occurred  either  just  before,  on, 
or  after  the  crest  of  volume. 

H.,  April  6,  II,  no.  2  (Fig.  11,  Plate  12). — ^About  ten  minutes  of  record  inter- 
vened between  the  preceding  extract  and  this  one.  The  subject  slept  regularly. 
Just  previous  to  4,  a  strong  gust  of  wind  through  the  open  window  awakened 
him,  so  that  he  ceased  snoring,  and  moved.  The  brain  volume  was  held  up  with 
smaller  pulse  for  three  breaths,  and  then  fell  so  low  that  the  recorder  had  to  be 
raised  artificially  at  the  mark  "  art."  The  breathing  became  increased  in  ampli- 
tude and  irregular  at  first,  and  then  decreased  in  amplitude  and  rate.  The  breath- 
ing wave  in  the  volume  almost  disappeared.  Somewhat  farther  along,  in  a  part 
of  the  record  not  reproduced,  the  assistant  spoke  and  aroused  the  subject  com- 
pletely.    The  volume  fell  about  i  cm.  more  at  that  time. 

H.,  January  2$,  I  (Fig.  12,  Plate  13). — This  record  and  the  others  to  be  repro- 
duced from  January  25  and  from  January  15,  were  taken  from  the  second  subject 
by  means  of  the  second  form  of  brain  plethysmograph,  and  while  he  was  lying 
down  on  his  back.  The  brain  curve  in  all  was  written  by  the  large-sized  piston 
recorder  (diameter  of  piston  is  8.1  mm. ;  ratio  of  movement  of  piston  to  movement 
of  writing-point  is  i  to  5.3).  This  extract  does  not  begin  at  the  beginning  of  the 
record.  A  part  is  omitted  in  which  the  subject  drowsed  off  somewhat  and  then 
aroused  himself  again ;  the  volume  rose  with  the  partial  sleep,  and  fell  again  with 
the  disturbance.  So  the  reproduced  portion  begins  where  the  subject  had  just 
been  moving,  had  adjusted  himself  and  was  so  drowsy  that  he  went  to  sleep 
quickly.  As  usual,  there  were  several  alternations  of  decreased  and  increased 
breathing  in  both  chest  and  abdomen,  with  accompanying  increase  and  decrease 
of  volume.  The  increase  in  breathing  usually  began  a  little  before  the  fall  of 
volume.  The  last  changes  from  restricted  to  freer  breathing  were  less  abrupt, 
and  the  respiration  then  became  more  regular,  with  an  amplitude  intermediate 
between  the  extremes.  During  the  remainder  of  the  chart,  in  which  the  subject 
slept  soundly,  only  small  alternations  in  breathing  can  be  detected,  more  certainly 
in  the  abdomen  than  in  the  chest.  Measurement  from  the  beginning  of  the 
record  shows  that  an  increase  corresponds  to,  or  begins  just  before  a  fall  of 
volume  of  a  Traube-Hering  wave. 

If  we  measure  the  level  of  brain  volume  from  the  bottom  of  the  pulse-beat, 
we  find  that  the  curve  rose  nearly  4  cm.  as  the  subject  went  to  sleep.  The 
recorder  was  dropped  artificially  at  the  mark  "  art."  With  increase  in  volume, 
the  size  of  the  pulse  showed  a  tendency  to  increase  somewhat  at  first,  but  soon 


2  2  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

reached  a  limit  and  began  to  decrease;  and  at  the  height  of  volume  the  pulse  was 
relatively  small.  The  cause  of  this  decrease  seems  to  be  a  restriction  to  the  rise, 
and  there  is  a  more  or  less  definite  line  beyond  which  the  curve  does  not  go.  Even 
the  general  volume  would  probably  have  risen  farther  otherwise.  In  the  Traube- 
Hering  wave  there  is  a  small  pulse  at  the  crest  of  volume,  a  larger  pulse  at  the 
trough  of  volume.  Towards  the  end  of  the  extract  the  volume  had  fallen  a  little, 
and  the  pulse  became  correspondingly  larger.  The  respiratory  wave  in  the 
volume  is  not  so  evident  as  in  other  records,  but  it  can  be  followed  in  an  imaginary 
line  connecting  the  lowest  point  of  the  pulse-beats  during  sleep. 

In  some  records  taken  under  these  conditions,  the  subject  slept  for  some  time 
with  periodic  variations  of  breathing  and  volume  like  those  discussed  in  previous 
descriptions.  In  other  records  he  slept  evenly  for  fifteen  minutes  or  more,  with 
the  brain  volume  uniformly  high  and  pulse  small.  More  often  in  even,  regular 
sleep,  the  volume  was  somewhat  lower  and  pulse  larger,  as  at  the  end  of  this 
extract;  the  tracings  taken  just  after  the  part  here  reproduced  show  that  he 
contin-ued  to  sleep  with  the  curve  usually  at  about  such  a  level. 

H.,  January  15,  II  {ist.  ext.)  (Fig.  13,  Plate  14). — This  is  an  extract  from 
a  record  taken  with  an  arrangement  similar  to  that  used  in  January  25,  I.  It  is 
reproduced  in  order  to  show  the  appearance  of  the  Traube-Hering  wave  under 
these  conditions  when  the  subject  is  sleeping  lightly,  and  with  marked  periodic 
variations  in  depth  of  breathing.  It  will  be  seen  that  the  pulse  is  large  at  the 
trough,  and  small  at  the  crest  of  the  wave.  Furthermore,  each  wave  reaches  a 
limit  of  height  that  is  almost  exactly  the  same  in  all.  Measurement  at  the  begin- 
ning of  the  original  record  shows  that  the  breathing  curves  must  be  shifted 
backward  about  2  mm.  in  order  that  corresponding  points  of  the  breathing  and 
volume  curves  will  be  in  a  vertical  line.  It  will  then  be  found  that  the  increase 
in  breathing  begins  slightly  before  the  fall  of  volume. 

H.,  January  15,  I  (Fig.  14,  Plate  15). — About  twenty  minutes  of  record 
preceded  the  portion  reproduced,  in  which  the  subject  had  gone  to  sleep  and  slept 
evenly ;  the  volume  had  risen  as  he  went  to  sleep,  and  remained  uniformly  high 
with  small  pulse,  except  for  a  shallow  Traube-Hering  wave.  Even  this  Traube- 
Hering  was  practically  absent  during  the  last  five  minutes,  in  which  the  subject 
had  snored  more  definitely.  The  first  of  this  extract  shows  a  high  volume,  small 
pulse,  and  regular  breathing,  with  a  check  in  the  inspiratory  fall  due  to  snoring. 

Before  the  experiment  began,  a  key,  which  was  in  circuit  with  the  lower 
indicator,  had  been  placed  on  a  chair  beside  the  bed,  and  within  easy  reach  of 
the  subject.  He  was  instructed  to  reach  and  press  the  key  whenever  he  realized 
the  he  had  awakened  out  of  a  sleep.  The  mark  at  i  is  such  a  signal.  It  will 
be  seen  that  the  awakening  was  accompanied  by  a  greatly  increased  amplitude  of 
chest  and  abdominal  breathing,  and  somewhat  decreased  rate.  After  the  subject 
was  awake,  the  rate  of  breathing  was  not  again  increased,  the  amplitude  of  the 
abdominal  remained  larger  than  during  sleep,  but  the  amplitude  of  the  chest 
became  smaller  than  in  sleep.  The  brain  volume  at  first  showed  a  tendency  to 
rise  with  very  restricted  pulse,  then  fell  with  increasing  pulse  to  a  level  more 


VOLUME  OF  THE   BRAIN  AND   OF  THE   PERIPHERY  23 

than  6  cm.  lower.  At  the  lowest  level,  and  at  the  trough  of  the  strong  breathing 
wave  which  appeared,  the  pulse  was  smaller  again.  The  volume  reaction  began  at 
least  as  early  as  the  change  in  breathing. 

In  view  of  the  discussion  of  curves  which  will  be  given  later,  it  should 
be  noted  that  when  the  subject  pressed  the  key,  particularly  when  he  began  to 
reach  for  it  as  indicated  by  the  change  in  chest  breathing,  the  brain  volume  had 
not  shown  more  than  half  its  total  fall.  Yet  he  was  well  enough  awake  to 
remember  all  about  his  actions  when  he  awakened  again  and  reported  an  hour 
afterward.  He  must  have  awakened,  realized  the  situation,  and  gotten  the  action 
under  way  by  this  time. 

H.,  January  25,  II  (Fig.  15,  Plate  16). — At  the  end  of  the  extract  from 
January  25,  I,  the  brain  curve  had  fallen  to  a  point  just  below  its  highest  level 
Since  that  time,  nearly  an  hour,  the  subject  had  slept  with  only  one  serious  dis- 
turbance, and  the  brain  curve  had  otherwise  remained  in  practically  the  same 
condition.  Such  is  the  state  in  which  we  find  it  at  the  beginning  of  this  selection. 
The  subject  was  snoring  somewhat,  a  Traube-Hering  wave  was  traceable  in  the 
brain,  and  the  respiratory  wave  in  the  volume  was  fairly  large. 

Just  before  /,  there  was  a  noise  outside  the  building,  which  disturbed  and 
awakened  the  subject.  The  result  was  an  increased  and  freer  breathing;  in  two 
places  the  pneumograph  tracing  was  disturbed  by  movement;  finally,  after  he 
was  awake,  the  amplitude  of  chest  breathing  became  rather  less  than  during  sleep, 
that  of  the  abdomen  decreased  but  remained  larger  than  during  sleep.  The  brain 
volume  increased  with  smaller  pulse  for  a  short  time,  and  then  fell  with  larger 
pulse  to  a  level  between  3  cm.  and  4  cm.  lower  than  during  sleep;  in  the  last 
part  of  this  fall,  the  pulse  became  smaller  with  the  decreasing  volume.  The 
respiratory  wave  in  the  volume  was  reduced. 

The  subject  remained  awake,  and  the  drum  was  run  for  about  five  minutes; 
the  experiment  was  then  stopped  and  an  introspection  taken.  The  subject 
reported  that  he  went  to  sleep  soon  after  the  experiment  started.  Something 
(the  disturbance  spoken  of  above)  half  waked  him,  and  he  wanted  to  press  the 
key,  but  "  couldn't  bring  himself  to  do  it."  He  then  went  to  sleep  again.  The 
next  he  knew  was  being  awakened  by  the  outside  noise,  which  he  heard  more 
as  a  dream  than  as  a  full  realization  of  it. 

Result  with  the  Subject  Lying  on  his  Side 
H.,  March  /,  III  (Fig.  16,  Plate  17). — In  this  record  the  subject  was  lying  on 
his  back,  but  with  his  head  turned  far  to  the  right.  He  had  been  sleeping  during 
the  last  fifteen  minutes,  with  no  change  in  the  curve  except  a  periodic  increase  of 
breathing,  and  accompanying  fall  of  volume  of  a  Traube-Hering  wave.  The 
chest  pneumograph  (the  lower  respiratory  curve)  was  on  too  loosely,  so  that  it 
only  gave  a  tracing  at  the  periods  of  greatest  depth  of  breathing.  The  second 
form  of  brain  plethysmograph  was  used,  and  was  connected  to  the  large  piston 
recorder.     At  the  beginning  of  this  extract,  the  volume  was  high  and  the  pulse 


24  STUDIES  IN  THE  CIRCULATION  AND  SLEEP 

small.  At  J,  the  light  in  the  sleeping  room  was  turned  on ;  at  ^  (the  mark  was  a 
little  late),  the  door  into  the  sleeping  room  was  opened.  Both  stimuli  disturbed 
the  subject  and  gave  an  increase  in  breathing  and  fall  of  volume  with  larger 
pulse.  Under  a  the  recorder  was  raised  artificially.  Ait  5,  I  spoke  to  the  subject 
and  asked  him  to  wake  up  but  not  move.  The  awakening  was  accompanied  by 
increased  breathing.  When  he  was  awake,  the  breathing  decreased  again,  but 
not  to  the  degree  found  in  sleep.  The  volume  of  the  brain  fell  with  a  larger 
pulse.  The  subject  reported,  when  the  drum  stopped,  that  he  remembered  he 
was  dreaming  just  before  he  awoke. 

Results  with  the  Subject  Sitting  Propped  Up 

The  next  records  to  be  described  were  taken  when  the  subject  was  sitting 
propped  up ;  his  legs  lay  on  the  bed ;  his  body  and  head  rested  against  a  support 
inclined  at  an  angle  of  about  50°  with  the  bed.  All  curves  from  the  first  sub- 
ject were  obtained  by  means  of  the  first  form  of  brain  plethysmograph,  while  the 
second  form  of  brain  plethysmograph  was  used  for  all  those  to  be  reproduced 
from  the  second  subject. 

Tests  of  the  influence  of  movements  in  the  case  of  the  second  subject  showed 
practically  no  effects.  With  the  first  subject,  a  scalp  tracing  showed  the  same 
fluctuations  on  account  of  movements,  that  were  found  when  he  was  lying  down, 
only  they  were  not  so  large  in  the  inclined  position.  But  these  changes,  except  the 
breathing  wave,  were  usually  of  a  quite  different  direction  from  the  brain  volume 
change,  and  were  nearly  always  easily  distinguished  by  their  abruptness.  Most 
of  the  records  were  unquestionable.  Furthermore,  it  would  be  difficult  to  use  the 
apparatus  for  elimination  of  movement  in  this  position.  It  could  only  be  done 
by  suspending  it  from  in  front  of  the  subject,  and  supporting  it  by  a  counter- 
balancing weight.  Inasmuch  as  this  would  be  inconvenient  to  the  sleeper,  and 
everything  except  the  breathing  wave  was  certain  anyway,  this  was  considered 
unnecessary. 

/.,  January  50,  ///  (Fig.  17,  Plate  18). — The  diameter  of  this  record  was 
reduced  one-tenth  in  the  reproduction.  The  curves  in  order  fromi  the  top  down 
are  the  indicator  line,  the  chest  breathing,  the  hand  volume,  and  the  brain  volume. 
The  hand  curve  was  written  with  the  first  moderate  sized  recorder,  the  brain 
volume  was  written  by  the  large  recorder.  The  record  was  begun  with  the  light 
turned  on  in  the  sleeping  room,  so  that  the  assistant  could  easily  watch  the  subject 
through  the  door.  This  did  not  trouble  him,  and  he  went  to  sleep  slowly  and 
gradually.  About  eight  minutes  of  the  record  is  omitted  before  the  beginning  of 
the  part  reproduced.  In  this  omitted  portion,  the  brain  volume  rose  only  slightly ; 
the  hand  volume  rose  several  millimeters. 

At  a,  the  rate  of  rotation  was  decreased;  and  in  making  the  change  the  drum 
was  practically  stopped,  and  caused  two  marked  lines  in  each  tracing,  which  are 
useful  as  lines  of  reference.  At  i,  the  light  in  the  bedroom  was  turned  out.  At 
2,  it  was  again  turned  on.     At  3,  the  assistant  entered  the  bedroom.     The  subject 


VOLUME  OF  THE  BRAIN  AND  OF  THE  PERIPHERY        25 

was  apparently  sleeping.  At  4,  the  assistant  came  out,  and  at  5,  the  light  was 
turned  off.  Unlike  most  experiments,  the  assistant  did  not  remain  in  the  subject's 
room  during  this  test.  A  Httle  later  in  the  record  than  the  part  reproduced,  the 
assistant  again  entered  the  bedroom.     The  subject  was  soundly  asleep. 

It  will  be  seen  that  as  sleep  came  on,  the  brain  volume  increased  one  and 
one-half  centimeters  if  measured  from  the  bottom  of  the  pulse,  over  three  centi- 
meters if  measured  from  the  top  of  the  pulse.  The  size  of  the  pulse  from  the 
brain  increased  much  more  in  proportion  to  the  increase  in  volume  than  it  did 
when  the  subject  was  lying  down.  The  volume  of  the  hand  rose  only  slightly, 
and  then  fell  again  during  the  latter  part  of  the  record.  It  showed  more  violent 
reactions  to  disturbances  than  the  brain,  although  both  curves  went  down  at  such 
times.  The  Traube-Hering  wave  in  the  volume  became  more  marked  as  the 
subject  went  to  sleep;  the  accompanying  breathing  changes  were  less  certain  than 
in  other  records.  Measurement  from  the  lines  of  reference,  and  allowing  for 
any  change  of  level,  shows  that  with  few  exceptions  the  waves  were  very  nearly 
parallel  in  time  in  the  two  curves ;  usually  they  did  not  vary  from  each  other  by 
more  than  two  or  three  pulse-beats.  The  breathing  wave  in  the  volume  was 
small;  it  became  greater  in  the  record  following  the  part  reproduced. 

The  vertical  breaks  in  the  tracings  are  due  to  folding  the  original  in  storing  it. 

/.,  February  6,  II,  no.  J  (Fig.  18,  Plate  19). — This  is  another  study  of  the 
changes  in  going  to  sleep  propped  up.  The  tracings  from  the  top  down  are  the 
indicator,  the  chest  breathing,  the  volume  of  the  hand,  and  the  volume  of  the  brain. 

On  account  of  the  expense  of  publication,  about  five  minutes  of  the  beginning 
of  this  record  are  omitted  from  that  reproduced.  In  it  the  brain  volume  had 
increased  i  cm.  with  considerable  increase  in  size  of  pulse.  At  a,  the  drum  was 
stopped  for  a  moment,  which  gives  lines  of  reference.  At  b,  the  brain  recorder 
was  dropped  artificially ;  here  also  the  record  is  blurred  by  folding.  At  /,  there 
was  a  slight  noise,  and  the  assistant  noted  that  the  subject  seemed  to  be  going  to 
sleep.  At  2,  he  was  snoring  and  sleeping  soundly.  The  volume  of  both  brain 
and  hand  increased  as  the  subject  went  to  sleep.  The  size  of  pulse  from  the 
brain  was  markedly  increased  in  proportion  to  the  change  of  volume.  The  pulse 
from  the  hand  was  not  definitely  changed.  The  Traube-Hering  wave  became 
fairly  marked  with  oncoming  of  sleep,  and  was  practically  parallel  in  time  in  the 
two  curves;  it  did  not  always  correspond  in  size  in  the  two.  There  was  a  tend- 
ency for  freer  breathing  to  accompany  a  fall  of  volume,  but  the  periodicity  in  the 
breathing  was  not  so  clear  as  that  in  the  volume. 

J.,  February  6,  II,  no.  2  (Fig.  19,  Plate  19). — This  is  an  extract  selected  from 
the  same  record,  and  was  taken  about  ten  minutes  later.  It  is  given  to  show 
the  large  respiratory  wave  which  had  come  into  both  brain  and  hand  curves.  The 
subject's  breathing  was  deep  and  labored.  The  volume  of  brain  and  hand  had 
not  changed  materially.  A  period  of  freer  breathing  for  three  breaths  was  accom- 
panied by  a  temporary  fall  of  volume. 

H.,  March  50,  I  (Fig.  20,  Plate  20). — In  this  and  the  following  records  from 
the  second  subject,  the  curves  in  order  from  the  top  down  are  the  abdominal 


26  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

breathing,  the  chest  breathing,  the  operator's  indicator  line,  the  indicator  line 
used  by  the  assistant  in  the  bedroom  and  the  brain  volume  curve.  The  brain 
volume  in  this  and  all  similar  cases  was  written  by  means  of  the  large  piston 
recorder. 

At  a  and  b,  the  brain  recorder  was  artificially  lowered.  The  subject  was 
awake,  but  drowsy  at  the  start.  He  went  to  sleep  quickly.  At  i,  the  assistant 
noted  that  the  subject  had  been  moving  his  body  and  arms.  During  the  part 
of  the  record  just  after  that  reproduced,  the  assistant  noted  that  the  subject 
was  breathing  deeply  and  was  asleep. 

It  will  be  seen  that  the  brain  volume  rose  approximately  7  cm.  as  the  subject 
went  to  sleep.  It  fell  temporarily  with  the  disturbance  at  i.  At  its  height  in  the 
neighborhood  of  b,  this  increase  of  volume  reached  a  line  beyond  which  it  could 
not  go ;  and  there  was  a  consequent  restriction  of  pulse  like  that  found  in  previous 
records  with  the  same  instruments  and  from  the  same  subject  lying  down. 
Near  the  end  of  the  extract  the  curve  fell  again,  with  increased  size  of  pulse,  to  a 
level  which  was  still  distinctly  higher  than  that  during  waking  condition.  It  is 
approximately  at  this  level  that  the  subject  usually  sleeps,  as  we  shall  find  in 
other  records.  There  is  a  considerable  respiratory  wave  in  the  curve  at  the  end. 
Except  for  the  restriction  of  the  pulse  as  the  volume  reaches  its  limit  of  rise,  the 
increase  in  size  of  pulse  was  enormous  compared  with  the  increase  of  volume. 

H.,  April  5,  //  (Fig.  21,  Plates  21  and  22).' — The  subject  had  slept  through 
the  preceding  record,  about  forty  minutes  in  length.  He  had  been  aroused  and 
was  awake  at  the  beginning  of  this.  At  5,  he  moved  a  little.  The  fall  at  a  was 
probably  partly  artificial,  in  that  a  bubble  of  air  apparently  escaped  past  the 
piston.  At  6,  he  began  to  breathe  more  deeply.  Before  7  he  was  snoring  per- 
ceptibly; then  he  stopped,  then  began  again.  At  8,  he  snored  more.  The  fall 
at  b  was  artificial.     At  p,  he  was  snoring  loudly  and  regularly. 

At  the  beginning  of  the  curve  there  seems  to  be  a  line  below  which  the  volume 
cannot  fall,  the  level  at  which  the  scalp  becomes  taut  and  will  not  sink  further. 
As  in  all  cases,  the  volume  of  the  brain  increased  when  the  subject  went  to  sleep. 
Every  indication  of  sleep,  as  at  6,  brought  with  it  a  rise  of  volume.  Every 
disturbance  of  sleep,  as  at  7,  was  accompanied  by  a  fall  of  volume.  The  curve 
from  8  through  p  and  beyond  shows  the  level  at  which  the  subject  usually  sleeps. 
A  majority  of  the  records  taken  under  similar  conditions  show  this  type  of  curve. 
With  the  increase  of  volume,  there  was  an  increase  in  size  of  pulse  which  was 
very  large  in  proportion  to  the  change  of  volume 

During  the  first  part  of  this  record  there  was  a  periodically  restricted  and  freer 
breathing,  which,  as  usual,  accompanied  the  rise  and  fall  of  a  Traube-Hering 
wave  in  the  volume.  As  sleep  became  deeper,  the  average  depth  of  breathing 
was  increased,  and  the  restricted  phases  became  less  marked  until  the  periodicity 
could  not  be  traced  with  certainty.  The  wave  of  volume  became  a  Traube-Hering 
wave  in  sleep. 

3  The  pulse  form  was  slightly  obscured  by  the  necessity  of  tooling  out  the  engraving, 
particularly  in  the  first  part  of  the  record.  On  account  of  the  length  of  this  record,  it  was 
necessary  to  reproduce  it  in  two  parts. 


VOLUME  OF  THE   BRAIN  AND   OF  THE   PERIPHERY  27 

There  was  a  considerable  respiratory  wave  in  the  volume  during  deep  sleep. 
Near  the  end,  the  drum  was  run  rapidly  for  a  short  distance.  Measuring  from 
the  ends  of  this  space,  it  is  found  that  the  trough  of  the  volume  wave  occurred 
near  the  end  of  the  check  in  inspiration  due  to  snoring;  the  crest  of  volume 
occurred  in  the  latter  part  of  expiration. 

There  is  often  a  sudden  fall  in  the  volume,  particularly  from  the  crest  of  a 
Traube-Hering,  which  does  not  involve  a  break  in  the  pulse  like  that  due  to  move- 
ments. Such  a  fall  is  seen  at  c.  It  is  doubtless  due  to  a  quick,  weak  heart-beat 
followed  by  a  delayed  one,  such  as  we  shall  see  much  more  of  in  studying  the 
heart-rate  changes  later.  There  are  in  all  these  records  important  variations  of 
pulse  form  which  will  also  be  studied  later. 

H.,  March  50,  //  (Fig.  22,  Plate  23). — In  reproducing,  the  diameter  of  this 
record  was  multiplied  by  three- fourths.  The  subject  was  asleep  at  the  start,  and 
had  been  sleeping  uniformly  at  this  level  for  about  twenty-five  minutes.  At  2, 
he  moved  considerably,  as  shown  also  by  the  breathing  tracings.  He  seemed  very 
nearly  awake,  although  he  did  not  remember  it  when  asked  to  give  introspections 
one-half  hour  later.  At  j,  the  assistant  noted  that  he  was  breathing  more  regu- 
larly again.  At  4,  the  assistant  made  a  noise  and  the  subject  stopped  snoring  and 
moved  a  little  afterwards.  He  then  remained  practically  awake  during  the  fol- 
lowing twenty  minutes  until  the  drum  was  stopped  (most  of  which  is,  of  course, 
not  reproduced). 

The  brain  volume  fell  so  much  at  2  that  I  had  to  raise  the  recorder  twice 
artificially.  It  rose  again  as  the  subject  returned  to  sleep,  and  decreased  again 
at  4.  A  large  increase  in  size  of  pulse  accompanied  a  rise  of  volume.  A  decrease 
accompanied  a  fall  of  volume. 

The  breathing  was  increased  with  a  fall  of  volume  at  disturbances.  It  was 
less  in  waking  condition  than  during  sleep.  The  abdominal  breathing  was  deeper, 
the  chest  shallower,  during  the  sleep  between  j  and  4  than  in  that  at  the  beginning 
of  the  record.     A  considerable  respiratory  wave  was  found  in  sleep. 

H.,  March  28,  I  (Fig.  23,  Plates  24  and  25).* — The  diameter  of  this  curve  is 
reduced  one-half  in  the  reproduction.  The  pulse  form  is  therefore  obscured ;  but 
this  will  be  shown  in  more  detail  later. 

The  subject  was  very  sleepy  from  the  start,  and  it  was  reported  by  the  assistant 
in  the  bedroom  that  he  nearly  went  to  sleep  during  the  preliminary  testing  before 
a.  And  there  was,  correspondingly,  an  increase  in  volume  and  size  of  pulse  from 
the  brain.  At  a,  the  drum  was  stopped,  the  lights  in  the  sleeping-room  were 
turned  out,  and  the  regular  test  was  begun.  At  b,  the  brain  curve  was  dropped 
artificially.  At  /,  the  subject  moved.  At  2,  there  was  a  slight  noise  of  someone 
passing  outside.  At  5  and  4,  the  subject  moved.  At  5,  he  snored  a  little  and  then 
breathed  more  deeply.  At  6,  he  was  sleeping  well,  not  snoring  much.  At  7,  the 
clock  struck.  At  c,  the  assistant  made  some  noise  in  talking  through  the  tube. 
At  8,  the  subject  swallowed.  At  p,  he  was  snoring  louder.  At  10,  there  was  a 
noise  outside,  which  disturbed  the  subject  and  led  to  "increased  and  irregular 

*  On  account  of  the  length  of  this  record,  it  was  necessary  to  reproduce  it  in  two  parts. 


a8  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

breathing  temporarily.  At  ii,  he  had  practically  stopped  snoring.  At  12,  there 
was  the  light  noise  of  rain  outside. 

The  volume  and  size  of  pulse  from  the  brain  increased  as  the  subject  went  to 
sleep.  Corresponding  to  the  rapid  oncoming  of  sleep,  the  circulation  change 
reached  its  limit  in  a  comparatively  short  time.  As  the  volume  rose  to  its  limiting 
line,  the  size  of  pulse  was  again  restricted  as  in  the  records  previously  described. 
This  curve  illustrates  the  less  usual  type  of  sleep  in  which  the  volume  tracing  is 
held  up  near  such  a  limiting  line  during  a  great  part  of  the  time. 

With  every  disturbance  of  breathing,  with  increased  and  freer  breathing,  there 
was  a  corresponding  fall  of  volume.  Measuring  from  the  lines  of  reference  in 
the  first  part  of  the  record,  it  is  found  that  the  breathing  change  usually  begins  a 
little  before  the  fall  of  volume.  At  every  disturbance  noted  by  the  assistant, 
especially  j,  4,  8  and  10,  there  was  such  a  change  in  breathing  and  volume.  The 
fall  from  the  limiting  position  at  10  shows  characteristically  an  increase  and  then 
a  decrease  in  size  of  pulse.  There  were  the  usual  reverse  changes  as  the  subject 
returned  to  deep  sleep. 

There  was  not  so  much  snoring  and  not  so  large  a  respiratory  wave  as  usual. 

There  are  several  illustrations  of  the  short,  weak  heart-beat  followed  by  a 
delayed  one,  and  the  accompanying  brief  fall  of  the  needle,  as  in  the  other  records. 
These  are  seen,  for  example,  before  /,  before  and  after  2,  and  before  j  and  5. 

Results  with  the  Subject  Sitting  up,  Leaning  Forward 
Several  curves  were  taken  from  the  second  subject  to  find  the  change  in  the 
brain  when  he  went  to  sleep  sitting  up,  leaning  forward,  and  resting  his  chin  on 
a  cushioned  support.  In  these  curves,  gravity  had  an  influence  similar  to  that  in 
the  records  just  described ;  but  the  brain  substance  tended  to  press  forward  against 
the  skull  in  the  neighborhood  of  the  trephine.  Presumably  with  this  arrange- 
ment, the  changes  shown  in  the  tracings  would  be  more  completely  due  to  the 
changes  in  the  circulation  in  the  immediate  neighborhood  of  the  trephine,  less 
due  to  changes  in  a  large  section  of  the  cerebrum;  the  alteration  in  diameter  of 
the  brain  as  a  whole  would  not  exert  so  much  influence.  There  were  some 
difficulties.  The  slight  pressure  of  the  cerebro-spinal  fluid  apparently  served, 
with  the  second  form  of  brain  plethysmograph,  to  make  the  scalp  bulge  until  it 
was  nearly  taut,  and  thus  prevented  even  the  pulse  from  showing  itself  accurately. 
For  this  reason,  the  first  form  of  brain  plethysmograph  was  used  for  all  records. 
The  even  tension  of  the  rubber  in  this  served  to  keep  the  scalp  back  against  the 
firmer  substance,  which  never  protrudes  so  as  to  make  the  skin  taut.  Further- 
more, the  position  was  too  uncomfortable  for  the  subject  to  sleep  well.  Par- 
ticularly it  was  impossible  to  go  to  sleep  in  an  adequate  apparatus  for  elimination 
of  movement,  and  consequently  the  tracings  are  not  altogether  free  from  the 
effects  of  movement. 

I  shall  describe  three  extracts. 

H.,  August  I,  I  (Fig.  24,  Plate  24). — The  diameter  is  reduced  one-half  in  the 
reproduction.     The  chest  breathing  is  at  the  top ;  the  brain  curve  is  at  the  bottom. 


VOLUME  OF  THE  BRAIN  AND  OF  THE  PERIPHERY        29 

The  breathing  curve  is  somewhat  interfered  with  by  striking  at  the  bottom.  The 
subject  had  been  asleep,  had  been  disturbed,  and  was  partially  awake  at  the 
beginning  of  the  part  reproduced.  A  note  made  at  the  beginning  of  the  next 
paper,  at  which  time  the  tracing  was  entirely  similar  to  that  at  the  end  of  this 
paper,  states  that  the  subject  was  breathing  audibly,  as  though  sleeping  fairly 
soundly.     This  extract,  then,  will  represent  the  process  of  going  to  sleep. 

The  volume  and  size  of  the  pulse  from  the  brain  increased.  There  was  a 
wave  in  the  volume  such  that  a  small  increase  in  breathing  usually  accompanied 
the  fall  of  volume,  but  the  change  in  the  breathing  was  never  abrupt.  The 
respiratory  wave  in  the  volume  was  probably  in  part  due  to  the  breathing 
movements. 

In  other  cases  the  brain  volume  rose  as  much  or  more;  but  the  size  of  the 
pulse  was  sometimes  not  increased  so  much,  and  might  even  be  decreased  in  the 
latter  part  of  the  rise,  although  there  was  no  such  definite  limiting  line  as  was 
found  in  previous  records  with  the  second  form  of  brain  plethysmograph. 

H.,  July  20,  II,  no.  i  (Fig.  25,  Plate  25). — The  order  of  curves  from  the  top 
down  is  abdominal  breathing,  chest  breathing,  indicator  line,  and  brain  plethys- 
mograph. The  diameter  is  reduced  one-half.  The  subject  had  been  asleep,  had 
been  disturbed  and  moved,  and  this  extract  begins  immediately  after  the  dis- 
turbance. The  subject  was  probably  partly  asleep.  As  he  became  quiet  and 
returned  to  deeper  sleep,  the  brain  recorder  rose  without  constant  change  in  size 
of  pulse.  It  was  dropped  artificially  at  a.  At  b,  a  period  of  deeper,  freer 
breathing  was  accompanied  by  a  decreased  volume  and  size  of  pulse.  This  was 
followed  by  a  rise  of  volume  and  larger  pulse  as  the  breathing  returned  to  the 
sleeping  form. 

H.,  July  20,  II,  no.  2  (Fig.  26,  Plate  25). — The  diameter  of  this  also  is  reduced 
one-half.  The  subject  was  partially  asleep  at  the  beginning  of  this  extract  (about 
three  minutes  of  record  are  omitted  between  no.  i  and  no.  2).  He  began  to 
awaken  at  a.  The  recorder  fell  and  was  raised  artificially  at  h.  Movement  so 
obscured  this  and  other  awakenings  under  the  same  conditions  that  they  are  not 
entirely  reliable.  But  the  indications  are  always,  as  here,  that  awakening  is 
accompanied  by  fall  of  volume,  and  probably  decreased  pulse  generally. 

Compression  of  the  Jugulars 

Several  curves  were  taken  from  the  second  subject  to  show  the  effect  of  inter- 
ference with  the  venous  outflow  upon  the  brain  circulation.  Some  were  taken 
while  the  subject  was  sitting  propped  up,  others  while  he  was  lying  down  on  his 
back.  The  former  were  recorded  with  the  second  form  of  brain  plethysmograph, 
the  latter  partly  with  each  form  of  brain  plethysmograph.  The  subject  usually 
compressed  the  jugulars  himself.  His  fingers  were  placed  over  the  veins  before 
the  experiment  began.  At  a  signal  from  the  operator,  pressure  was  applied,  at  a 
second  signal  it  was  removed.     I  reproduce  two  tracings  to  illustrate  the  effect. 

H.,  July  17,  VII  (ist  ext.)  (Fig.  27,  Plate  26). — This  was  written  with  the 
second  form  of  brain  plethysmograph  while  the  subject  was  sitting  up.     It  will 


30  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

be  seen  that  compression  was  accompanied  by  increased  volume  and  smaller  pulse. 
A  part  of  the  restriction  of  pulse  was  apparently  due  to  reaching  a  limiting  level 
(on  account  of  the  taut  scalp  and  plugged  trephine)  like  that  sometimes  found  in 
deep  sleep.  But  a  comparison  of  curves  under  a  (during  normal)  and  b  (during 
compression)  at  approximately  the  same  level,  shows  that  the  decrease  was  not 
entirely  caused  by  this  process.  There  was  a  change  in  the  breathing  tracing 
probably  due  to  the  subject's  movements  in  applying  and  removing  compression; 
it  does  not  occur  in  many  records.  The  pulse  form,  which  is  shown  clearly  where 
the  kymograph  ran  more  rapidly,  will  be  discussed  later.  Although  the  piston 
recorder  did  not  leak  elsewhere  in  a  long  series  of  tests,  the  sudden  fall  when 
compression  was  removed  in  this  case  caused  a  bubble  of  air  to  escape  and 
necessitated  the  artificial  rise  under  c. 

H.,  July  17,  Vni  (ist  ext.)  (Fig.  28,  Plate  27). — This  is  an  extract  from  a 
much  longer  record.  It  was  taken  while  the  subject  was  lying  on  his  back,  with 
the  first  form  of  brain  plethysmograph.  It  represents  the  end  of  a  period  of 
compression  and  the  return  to  normal.  At  the  beginning  of  the  extract,  the 
kymograph  was  running  rapidly  to  show  the  pulse  form.  When  the  pressure  was 
removed,  the  volume  fell.  The  size  of  the  pulse  was  not  greatly  changed,  perhaps 
slightly  increased.  The  pulse  form  underwent  a  characteristic  change  which  will 
be  referred  to  later. 

Reactions  While  Awake 

Some  years  ago  I  published^  the  results  of  an  investigation  of  the  reactions  to 
stimuli  while  sitting  up  during  the  waking  condition.  The  first  subject  in  the 
present  study  served  as  subject  for  the  section  on  the  brain  circulation  in  the 
previous  work.  Since  that,  tests  have  been  made  of  the  waking  reactions  of  the 
second  subject  while  sitting  up.  Also  a  quite  extended  series  of  experiments, 
mostly  on  the  first  subject,  have  shown  the  effects  of  stimuli  during  the  waking 
condition  while  the  subject  is  lying  down  on  his  back.  With  the  second  subject 
sitting  up,  no  very  intense  stimuli  were  tried.  All  moderate  stimuli  of  every 
character  gave  an  increase  in  volume  and  size  of  pulse  from  the  brain.  Talking 
and  laughing,  on  account  of  the  irregular  breathing,  caused  an  irregular  tracing. 
The  experiments  were  not  nearly  so  thorough  as  in  the  earlier  work,  and  the 
results,  so  far  as  they  went,  were  entirely  similar  to  those  already  published  from 
the  first  subject.  For  this  reason  I  shall  not  reproduce  any  of  them  here,  but 
shall  turn  to  a  description  of  a  few  of  the  tests  with  the  first  subject  lying  down. 

J.,  January  50,  I  (Fig.  29,  Plate  28). — The  chest  breathing  curve  is  next  the 
indicator  line,  the  brain  curve  is  at  the  bottom,  and  the  curve  between  these  two  is 
from  the  hand.  At  5,  the  subject  attended  to  a  faint  watch  tick,  and  attempted 
to  get  the  attention  wave.  There  was  no  surprise  at  the  signals  to  begin  and  stop, 
and  it  required  considerable  effort.  At  6,  the  assistant  yelled  and  slammed  the 
door  of  the  subject's  room.     He  was  frightened,  and  did  not  get  over  the  feeling 

^  "  Organic  Changes  and  Feeling,"  American  Journal  of  Psychology,  1906,  Vol.  XVII, 
pp.  522-584. 


VOLUME  OF  THE  BRAIN  AND  OF  THE  PERIPHERY        3^ 

for  some  time.  The  attention  had  no  appreciable  effect  upon  the  hand  volume, 
but  caused  a  gradual  rise  of  volume  of  the  brain,  but  with  somewhat  smaller  pulse 
beat.     The  brain  gradually  returned  to  normal  afterward. 

The  fright  was  accompanied  by  a  rise  of  volume  of  the  hand  with  smaller 
pulse.  After  a  few  pulse  beats,  this  was  followed  by  a  brief  constriction.  The 
brain  showed  the  same  short  rise  of  volume  with  smaller  pulse,  followed  by  a 
period  in  which  the  volume  fell  part  way  toward  normal,  with  a  size  of  pulse 
nearly  (but  not  quite)  normal.  Volume  and  pulse  then  gradually  returned  to 
normal. 

/.,  October  22  (Fig.  30,  Plate  29). — The  chest  breathing  is  at  the  top,  the 
brain  record  is  next  below  the  indicator  line,  and  a  curve  from  the  foot  is  at  the 
bottom.  At  2,  a  man  walked  by  the  door,  but  the  subject  did  not  pay  much 
attention  to  him.  At  j,  or  just  before,  a  whistle  was  blown.  It  frightened  the 
subject,  although  not  severely.  The  result  was  an  increase  in  volume  of  the  brain. 
On  account  of  the  change  in  size  of  pulse  accompanying  the  wave  in  the  volume,  it 
is  impossible  to  be  certain  whether  the  reaction  caused  a  variation  in  size.  At  any 
rate,  there  was  no  marked  effect  on  the  pulse.  The  foot  tracing  rose  slightly, 
and  then  fell  considerably  below  normal.  Both  curves  then  gradually  returned 
to  normal. 

/.,  December  ip,  I,  Exp.  6  (Fig.  31,  Plate  30). — The  curves  from  the  top 
down  are  the  indicator  line,  the  chest  breathing,  the  hand  volume  and  the 
brain  volume.  Both  systems  of  tubes  were  leaking  slightly,  but  not  enough  to 
interfere  materially  with  these  experiments.  At  6,  the  assistant  made  a  loud 
noise,  whidh  so  frightened  the  subject  that  he  did  not  get  over  it  for  some  time. 
The  volume  of  the  hand  increased  for  a  few  pulse  beats,  with  a  pulse  somewhat 
smaller  than  normal,  then  decreased  below  normal  and  was  raised  artificially. 
The  brain  volume  increased  with  smaller  pulse,  then  dropped  slightly,  then  rose 
to  an  even  higher  level  with  a  pulse  somewhat  larger  than  at  first,  but  yet  less 
than  normal.     After  another  undulation  the  curve  returned  gradually  to  normal. 

/.,  December  ig,  I,  Exp.  g  (Fig.  32,  Plate  31). — This  is  a  later  extract  taken 
from  the  same  series  as  the  preceding  one.  At.p,  occurred  the  same  sort  of 
fright  as  at  6,  except  that  the  subject  got  over  it  more  quickly.  The  result  was 
a  rise  in  volume  of  the  hand  with  a  smaller  pulse,  followed  by  a  fall.  The 
brain  increased  in  volume  with  smaller  pulse,  and  then  gradually  returned  to 
normal,  the  size  of  pulse  becoming  normal  more  rapidly  than  the  volume. 

/.,  October  2g,  I  (Fig.  33,  Plate  29). — The  diameter  is  reduced  one-half.  The 
chest  breathing  is  above  the  indicator  line,  the  brain  curve  below  it.  The  curve  is 
slightly  marred  by  the  fact  that  the  piston  caught  in  three  places,  which  was  due 
to  a  particle  of  dust  accidentally  dropped  into  the  cylinder.  The  stimulus  at  2 
was  a  secondary  circuit  through  the  hand  of  the  subject;  an  exposed  wire  was 
used  as  an  electrode.  It  pained  the  subject  but  did  not  cause  contraction  of  the 
muscles  of  the  arm.  The  breathing  became  shallower  at  first,  then  deeper.  The 
brain  increased  in  volume  with  somewhat  smaller  pulse,  and  gradually  returned 
to  normal.     It  will  be  noticed  that  in  the  Traube-Hering  wave,  which  shows  better 


32  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

toward  the  end  of  the  extract,  the  pulse  is  larger  at  the  crest  of  the  wave  than  at 
the  trough.     This  is  not  the  rule,  however,  with  the  first  subject  lying  down. 

The  importance  of  the  pulse  form  in  all  these  curves  will  be  brought  out  later. 

Effects  of  Changes  in  Breathing 

Another  fact  of  importance  for  the  interpretation  of  the  sleep  records  is  the 
influence  of  artificial  changes  of  breathing.  Altogether,  I  studied  the  effects, 
particularly  on  the  brain  circulation,  of  the  following  conditions: — attempted 
expiration  with  closed  passages,  and  attempted  inspiration  with  closed  passages ; 
simple  holding  of  the  breath  in  inspiration  or  expiration;  artificial  snoring  pro- 
duced either  by  conscious  interference  with  intake  of  air,  or  by  interference  with 
both  intake  and  outgo ;  deep,  free  breathing ;  chest  breathing  as  distinguished  from 
natural  (chest  and  abdominal)  breathing.  The  chest  breathing  and  deep  breath- 
ing were  tested  mainly  with  the  subject  lying  down;  the  cessations  of  breathing 
mainly  with  the  subject  sitting  up  in  the  case  of  the  first  subject,  lying  down  in 
the  case  of  the  second;  the  artificial  snoring,  both  with  the  subject  sitting  up,  and 
with  him  lying  down.     I  shall  describe  a  few  typical  records. 

/.,  October  12,  IV  (Fig.  34,  Plate  32). — Most  of  the  results  with  a  cessation 
of  breathing  were  taken  early  in  the  course  of  the  experiments  when  I  was  still 
using  short  papers.  I  reproduce  a  paper  on  which  two  tests  were  made.  The 
second  one  ran  by  the  end  of  the  paper,  and  so  is  continued  at  the  beginning; 
its  curves  can  be  traced  with  ease  among  the  curves  of  the  first  test.  The  markers 
from  the  top  down  were  the  indicator  line,  the  chest  breathing,  the  hand  volume 
and  the  brain  volume.  The  record  was  from  the  first  subject  and  he  was  sitting 
up.  At  I,  the  subject  tried  to  draw  air  into  his  lungs,  but  held  his  nose  and 
mouth  closed  to  prevent  it.  The  hand  volume  seems  to  be  decreased,  although  the 
wave  in  the  tracing  obscures  this;  this  decrease  continues  after  free  breathing 
begins  again.  The  brain  volume  is  not  appreciably  affected  until  near  the  end 
of  the  restricted  breathing,  when  it  begins  to  increase;  this  increase  reaches  its 
crest  about  four  breaths  after  free  breathing  returns.  The  drum  was  stopped 
before  the  tracings  had  completely  returned  to  normal.  At  2,  the  subject  tried 
to  expire  forcibly  with  similarly  closed  passages.  The  result  in  the  hand  was  a 
brief  rise  of  volume  followed  by  a  fall.  In  the  brain  there  was  a  brief  rise  with 
larger  pulse,  followed  by  a  fall  toward  normal  with  smaller  pulse.  Another 
undulation  near  the  end  of  restricted  breathing  (probably  a  Traube-Hering)  was 
followed  by  an  increased  volume  and  larger  pulse  during  free  breathing.  Again 
the  tracings  had  not  returned  to  normal  when  the  drum  was  stopped.  "  Art "  on 
the  paper  signifies  an  artificial  change. 

I  chose  this  record  for  reproduction  because  it  shows  both  a  restricted  inspira- 
tion and  restricted  expiration.  It  should  be  added  that  the  fall  in  the  hand 
volume  was  usually  more  marked  than  in  this  case.  Another  record  of  restricted 
inspiration,  in  which  the  effort  was  probably  greater,  gave  a  brief  fall  in  the 
brain  with  smaller  pulse,  then  a  brief  rise  with  larger  pulse,  then  a  reaction 
similar  to  that  reproduced.     Simple  holding  of  the  breath  was  accompanied  by 


VOLUME  OF  THE   BRAIN  AND   OF   THE   PERIPHERY  33 

a  result  very  similar  to  the  first  test  on  the  paper  reproduced.  In  one  case  in 
which  the  breath  was  held  much  longer,  the  rise  in  the  brain  began  about  the 
same  time  after  the  beginning  of  the  period  of  checked  breathing,  reached  a 
relatively  high  level  at  the  end  of  that  period,  and  reached  its  crest  at  the  third 
breath  after  free  breathing  returned.  In  all  rises  of  volume,  the  pulse  increased 
in  size  with  rise  of  volume.  Holding  the  breath  gave  the  same  result  with  the 
second  subject,  except  that  there  was  a  greater  acceleration  of  the  rise  when  he 
began  to  breath  again. 

/.,  November  28,  III  (Fig.  35,  Plate  33). — This  is  from  a  record  taken  from 
the  first  subject.  He  was  lying  down  on  his  back  with  his  head  resting  on  a 
fairly  thick  pillow.  At  4,  deep,  slow  breathing  commenced.  The  result  was  a 
brief  rise  of  volume  of  both  brain  and  hand,  with  size  of  pulse  about  normal. 
This  was  followed  by  a  fall,  particularly  in  the  brain.  The  brain  curve  had  to  be 
raised  artificially.  The  pulse  averaged  somewhat  smaller  with  the  low  volume 
in  the  brain.  The  hand  tracing  soon  returned  to  practically  normal.  The  brain 
fell  a  little  more  even  after  the  close  of  the  part  reproduced,  and  continued  low 
throughout  the  period  of  deep  breathing. 

This  record  is  typical  of  those  of  deep  breathing  taken  when  the  subject  was 
lying  down.  Others  taken  when  the  subject  was  sitting  up  show  almost  no  effect 
upon  the  volume  of  either  brain  or  hand,  except  to  cause  a  large  breathing  wave 
in  it.     But  in  this  case  also,  if  there  is  any  change  of  level,  it  is  a  fall. 

To  show  the  effect  of  artificial  snoring,  I  reproduce  the  beginning  and  the  end 
of  records  of  two  periods  of  such  breathing  from  the  second  subject,  and  omit  the 
middle  portion  of  each  period. 

H.,  July  17,  VII  {2d  ext.)  (Fig.  36,  Plate  34,  and  Fig.  2,7,  Plate  35).— This 
was  taken  while  the  subject  was  sitting  propped  up,  and  by  use  of  the  second  form 
of  brain  plethysmograph.  The  chest  breathing  is  at  the  top,  the  brain  tracing 
at  the  bottom.  Artificial  snoring  began  at  the  signal  in  the  indicator  line;  the 
resistance  was  mainly  to  intake  of  air.  The  result  was  a  fall  of  volume  with 
small  pulse.  The  volume  remained  at  this  low-level  line  all  through.  The 
mark  in  the  indicator  line  in  the  latter  part  of  the  extract,  shows  where  artificial 
snoring  stopped.  It  will  be  seen  that  the  subject  breathed  more  deeply  during 
the  snoring,  and  this  was  followed  by  a  period  of  reduced  breathing.  The  volume 
rose  to  about  the  former  level  with  larger  pulse. 

H.,  July  17,  VIII  {2d  ext.)  (Figs.  38  and  39,  Plate  36). — This  was  taken  by 
means  of  the  first  form  of  brain  plethysmograph,  and  while  the  subject  was  lying 
down  on  his  back.  The  conditions  were  otherwise  similar  to  those  in  the  preced- 
ing case,  and  it  needs  no  further  description. 

Most  of  the  records  with  chest  breathing  as  distinguished  from  natural  breath- 
ing were  clear  and  unambiguous.  But  I  will  reproduce  none  of  them,  since  they 
show  nothing  particularly  characteristic,  and  are  so  large  that  it  would  be  expen- 
sive to  print  them.  They  were  taken  from  the  second  subject.  When,  in  attempt- 
ing to  breathe  more  with  his  chest,  the  subject  increased  markedly  the  total  depth 


34  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

of  breathing,  the  result  was  a  fall  of  volume  of  the  brain,  as  in  the  above  cases 
with  the  first  subject.     In  other  cases  there  was  no  appreciable  effect. 

I  regret  that  no  reliable  curves  were  taken  with  merely  slowed  and  shallow 
breathing. 

Delay  of  the  Circulation  Change 

I  wish  now  to  describe  a  series  of  curves  bearing  upon  the  temporal  relation  of 
the  reaction  in  the  brain  circulation  to  the  sleep  process. 

H.,  January  15,  II  {2d  ext.)  (Fig.  40,  Plate  37). — This  is  another  extract  from, 
a  curve  which  we  have  already  had  occasion  to  discuss  in  part.  Although  the 
volume  was  so  high  that  the  pulse  was  restricted,  the  subject  was  only  lightly 
asleep  when  this  extract  began.  At  i,  the  light  was  turned  on  and  off.  At  the 
drop  in  the  line  marked  2,  the  light  was  again  turned  on,  and  the  assistant  entered 
the  sleeping  room  and  spoke  to  the  subject.  At  3,  the  whistle  was  blown.  The 
curve  is  like  those  in  which  the  subject  had  his  head  turned  slightly  to  the  left 
side,  and  this  may  have  been  the  case,  although  the  assistant  did  not  report  the 
position  of  the  head  at  the  end  of  this  curve.  The  fact  to  which  I  wish  to  call 
attention  now  is  that  the  light  at  i  affected  the  subject  somewhat, — he  had  some 
memory  of  it  afterward, — but  there  was  no  appreciable  effect  upon  the  brain 
circulation.  With  the  light  and  entrance  of  the  assistant  at  2,  the  curve  was  at 
first  raised  slightly  (which  was  partly  movement,  however)  and  then  fell  to  a 
lower  level,  with  larger  pulse.  The  whistle  caused  a  still  further  fall  of  volume. 
That  the  subject  was  only  lightly  asleep  at  /  is  indicated  by  the  breathing  and  by 
the  fact  that  according  to  his  statement  at  the  end,  he  noticed  the  light.  At  2,  the 
subject  moved  and  understood  what  was  said  to  him.  That  i  should  have  caused 
no  reaction,  and  2  only  a  partial  reaction  which  was  completed  at  5,  suggests  that 
the  circulation  change  may  lag  behind  the  mental  process. 

On  several  different  occasions  when  the  first  subject  was  very  sleepy,  I  placed 
near  his  hand  a  key  in  circuit  with  the  time-maker  writing  on  the  drum.  He  was 
asked  to  sit  quietly  in  the  dark,  in  some  cases  leaning  his  head  on  a  support,  and 
allow  himself  to  go  as  nearly  to  sleep  as  possible.  Naturally  under  these  condi- 
tions, he  only  lost  consciousness  a  short  time  before  the  strain  of  the  position 
would  awaken  him.  Whenever  he  realized  that  he  had  awakened  from  even  a 
brief  period  of  sleep  or  drowsing,  he  pressed  the  key,  and  so  indicated  that  instant 
on  the  record.  A  few  records  were  taken  under  similar  conditions  except  with 
the  subject  lying  down.  But  at  these  times  he  usually  slept  deeply  and  often 
forgot  his  instructions  when  he  did  aiwake.  I  will  describe  two  extracts  from 
records  taken  under  such  conditions,  the  first  when  the  subject  was  sitting  up,  the 
second  when  he  was  resting  against  a  support  at  an  angle  of  60°  with  the  bed. 
The  curves  from  the  top  down  in  each  are  the  indicator  line,  the  chest  breathing, 
the  volume  of  the  hand,  and  volume  of  the  brain. 

/.,  November  28,  II  (Fig.  41,  Plate  38). — The  subject  was  very  sleepy  and 
would  no  sooner  awake  than  he  would  at  once  start  to  sleep  again.  At  a,  b,  c,  d, 
and  e,  he  pressed  the  key.     At  e,  there  was  some  noise  outside  and  he  awakened 


VOLUME  OF  THE  BRAIN  AND  OF  THE  PERIPHERY        35 

with  a  start  and  jumped.  The  position  of  the  jump  is  indicated  by  the  dis- 
turbance in  the  chest,  hand  and  brain  curves;  the  hand  tracing  was  entirely  dis- 
placed by  the  movement,  and  a  little  later  had  to  be  regulated  artificially  to 
prevent  its  interference  with  the  brain  curve.  The  subject  pressed  the  key  soon 
after  the  jump.  As  usual,  the  volume,  especially  of  the  brain,  increased  as  the 
subject  began  to  sleep,  and  decreased  as  he  awoke.  But  if  the  curves  are  reduced 
to  the  normal  level  of  the  needles,  and  allowance  is  made  for  the  displacement  of 
the  writing-points  from  vertical  as  measured  by  the  lines  of  reference  at  the 
beginning  and  end  of  each  paper  (in  this  case  the  correction  is  small),  then  it  will 
be  found  that  the  key  was  pressed  a  little  (two  or  three  pulse  beats)  before  or 
just  as  the  volume  curves  began  their  descent. 

J.,  December  ip,  II  (Fig.  42,  Plate  39). — This  is  one  illustration,  typical  of 
those  cases  in  which  the  subject  was  leaning  back  against  a  support.  Otherwise 
conditions  were  similar  to  the  above,  and  it  needs  no  further  description.  It 
will  be  seen  again  that  the  subject  pressed  the  key  just  before  the  curves  began 
their  descent. 

It  should  be  added  that  in  a  small  part  of  the  cases,  the  key  was  pressed  later, 
the  subject's  introspection  being  that  he  forgot  it  at  times  until  a  moment  had 
passed.  I  may  also  refer  again  to  the  description  of  H.,  January  15,  I,  given 
above. 

Summary 

I  shall  not  attempt  to  summarize  the  results  of  this  chapter  in  a  definite  number 
of  concise  statements.  But  I  shall  give  a  sort  of  abstract  of  what  is  shown  by  the 
records  taken  to  study  the  volume  of  the  brain  and  of  the  periphery  and  the 
breathing. 

In  all  positions  of  the  subjects,  and  whether  sleep  came  on  quickly,  gradually, 
or  with  a  series  of  interruptions,  the  volume  of  the  brain  was  markedly  increased 
as  sleep  came  on.  Counting  the  records  from  both  subjects,  there  were  altogether 
seventeen  cases  in  which  the  subject  went  to  sleep  lying  on  his  back,  which  are 
covered  by  adequate  evidence  as  to  when  the  subject  went  to  sleep,  and  in  which 
the  curves  are  so  nearly  perfect  that  there  can  be  no  possible  doubt  of  the  result. 
In  each  of  these  there  was  a  definite  and  significant  rise  of  volume  with  sleep. 
There  were  also  many  records  so  obscured  by  movement,  leaking  apparatus,  or 
other  cause,  that  no  conclusion  could  be  drawn  from  them  with  complete  certainty. 
But  so  far  as  anything  could  be  said,  they  indicated  a  larger  volume.  In  addition, 
a  large  number  of  tracings  were  made  in  connection  with  the  study  of  blood- 
pressure,  etc.,  to  be  discussed  later,  and  they  uniformly  show  the  same  fact. 
Fifteen  clear  cases  of  going  to  sleep  "  propped  up,"  and  three  cases  of  going  to 
sleep  sitting  up  leaning  forward,  gave  undoubted  increase  in  the  brain  volume; 
and  several,  less  perfect,  indicated  the  same  result  as  probable. 

One  record  was  taken  with  the  second  subject  sitting  propped  up  and  using  the 
first  form  of  brain  plethysmograph.  Under  these  circumstances,  the  brain  sub- 
stance falls  away  from  the  trephine  and  permits  the  pressure  of  the  rubber  to 


36  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

hold  the  scalp  taut,  except  when  a  rise  of  volume  raises  it.  Sleep  was  accom- 
panied by  a  rise  of  volume  and  large  pulse. 

One  case  in  which  the  second  subject  went  to  sleep  lying  on  his  right  side, 
and  two  in  which  he  was  lying  on  his  left,  showed  a  higher  brain  curve  with 
sleep.     There  was  never  a  fall  in  any  position. 

The  absolute  values  of  the  majority  of  volume  changes,  or  the  portions  of 
them  that  affected  the  region  under  the  plethysmograph,  were  between  0.3  cu.  cm. 
and  0.7  cu.  cm.  How  much  additional  change  in  any  case  was  compensated  for  by 
displacement  of  cerebro-spinal  fluid  or  by  compression  of  veins,  it  is  impossible 
to  say. 

There  was,  in  general,  an  increase  in  the  size  of  the  arterial  pulse  from  the 
brain,  accompanying  the  increase  in  volume  with  sleep.  The  tendency  was  to  a 
greater  increase  in  size  of  pulse  in  proportion  to  the  increase  in  volume  when  the 
subject  was  sitting  up,  than  when  he  was  lying  down.  Both  the  volume  change 
and  the  size  of  pulse  are  limited  by  the  fact  that,  particularly  with  the  second 
form  of  brain  plethysmograph,  there  is  a  fairly  definite  upper  limiting  line  beyond 
which  the  curve  cannot  rise.  There  is  likewise  a  similar  lower  limiting  line  which 
marks  the  low  level  of  the  curve.  As  these  lines  are  approached,  the  pulse  must 
be  restricted.  These  lines  probably  mark  where  the  scalp  covering  the  trephine 
becomes  taut.  When  the  support  underneath  is  sufficiently  removed,  which  never 
happened  except  sometimes  with  the  second  subject  when  he  was  sitting  up,  the 
scalp  may  be  forced  in  until  it  is  taut.  This  position  is  not  absolutely  definite, 
since  the  neighboring  scalp  can  yield  somewhat.  When  the  brain  begins  to  even 
slightly  plug  the  trephine,  there  is  perhaps  a  local  rise  of  pressure  of  cerebro- 
spinal fluid  to  a  certain  extent,  due  to  restriction  of  venous  outflow,  which  causes 
the  scalp  to  bulge  until  it  becomes  taut.  Hence  the  advantage  of  the  first  form 
of  brain  plethysmograph,  in  which  the  tension  of  the  rubber  overcame  the  pressure 
of  fluid,  and  pressed  the  scalp  back  against  the  firmer  substance.  The  first  form 
of  plethysmograph,  then,  probably  gives  a  more  accurate  record  of  the  changes  in 
the  brain  substance  itself,  free  from  interfering  processes.  Even  here,  there  is, 
under  exceptional  conditions,  as  when  the  second  subject  leans  forward  or  lies 
on  his  face,  the  possibility  of  a  much  less  definite  limitation  of  rise  by  the 
plugging  of  the  trephine. 

Throughout  the  period  of  sleep  the  volume  of  the  brain  remains  higher  than 
in  the  waking  condition.  Stimuli  given  during  sleep,  but  not  strong  enough 
to  awaken  the  subject,  usually  cause  either  a  fall  of  volume  of  the  brain  with 
decreased  pulse  (except  as  the  pulse  is  modified  by  removal  of  the  above  restric- 
tions) or  a  level  or  even  slightly  raised  volume  for  a  few  pulse-beats  followed  by 
such  a  fall.  There  were  twenty-one  clear  cases  which  were  not  obscured  by 
movement  or  other  cause,  taken  when  the  subject  was  sleeping  on  his  back; 
twenty-two  such  cases  were  taken  when  the  subject  was  sleeping  propped  up; 
and  one  was  taken  when  he  was  sitting  up  leaning  forward.  All  of  these  gave  the 
above  result.  Several  others  were  so  obscured  by  movement  that  no  certain  con- 
clusion could  be  drawn.  Three  caused  the  slight  rise  for  a  few  pulse-beats 
without  being  followed  by  a  definite  fall. 


VOLUME  OF  THE   BRAIN  AND   OF  THE   PERIPHERY  37 

Waking  brings  with  it  a  fall  of  brain  volume,  and  altogether  the  reverse  of 
the  changes  brought  about  by  going  to  sleep.  Of  cases  in  which  the  curves  were 
reliable,  fourteen  taken  when  the  subject  was  lying  on  his  back,  nine  taken  when 
he  was  sitting  propped  up,  and  four  taken  when  he  was  sitting  up  leaning  forward, 
all  gave  a  fall.  Likewise  three  cases  in  which  the  second  subject  was  lying  on 
his  right  side,  and  one  in  which  he  was  lying  on  his  left,  resulted  in  a  fall.  Two 
or  three  cases  showed  a  short  rise  preceding  the  fall.  It  should  be  emphasized 
that  there  was  the  same  fall  even  when  the  subject  was  awakened  with  a  start  by 
a  strong  stimulus,  although  many  such  records  were  of  course  obscured  by  move- 
ment. Those  records  injured  by  movement  are  at  least  consistent  with  this 
conclusion. 

I  have  attempted  to  study  the  records  taken  at  different  times  during  the  night, 
to  determine  whether  there  is  any  variation  in  tihe  volume  of  the  brain  that  can  be 
correlated  with  the  supposed  curve  of  depth  of  sleep.  I  have  not  been  able  to 
arrive  at  any  definite  conclusion  except  that  the  highest  volume,  that  which 
with  the  second  form  of  brain  plethysmograph  approaches  a  limiting  line,  is 
usually  found  soon  after  the  subject  goes  to  sleep,  and  as  a  rule  disappears  within 
fifteen  to  twenty-five  minutes  at  the  most.  During  the  greater  part  of  sleep,  the 
brain  curve  is  at  a  level  a  little  below  this  extreme.  Of  course,  when  sleep  is 
obviously  light,  the  circulation  is  more  nearly  in  the  waking  condition,  although 
sometimes  the  volume  then  is  higher  than  one  might  expect.  I  have  been  unable 
to  find  any  other  definite  variation  of  the  curve.  But  the  effects  of  movement  and 
changes  of  temperature  at  different  places  in  several  records  are  so  great  that  it 
is  difficult  to  draw  any  conclusion  on  this  point. 

Neither  one  of  the  subjects  very  often  reported  a  dream.  In  the  two  or  three 
cases  found,  in  which  the  sleeper  awakened  from  a  dream  and  reported  it,  I 
noticed  that  there  had  been  a  more  or  less  irregular  disturbance  (fall  and 
recovery)  of  the  curve  for  a  few  minutes  before.  This  suggests  that  dreams  are 
a  disturbance  of  sleep,  and  that  they  are,  sometimes  at  least,  rather  discontinuous 
and  irregular,  more  so  than  the  subject  appreciates. 

Compression  of  the  jugulars  while  the  subje-ct  was  awake  caused  a  rise  of 
volume  of  tfhe  brain,  generally  with  smaller  pulse.  Stimuli  while  the  subject  was 
awake  caused  an  increase  in  brain  volume.  When  the  subject  was  sitting  up,  this 
increase  in  volume  was  accompanied  by  a  larger  pulse.  When  he  was  lying  down 
(this  applies  only  to  the  first  subject)  the  rise  in  volume  was  nearly  always  accom- 
panied by  a  smaller  pulse;  in  only  two  or  three  cases  out  of  thirty  was  there  a 
slight  increase.  In  reaction  to  strong  stimuli,  with  which  tihe  circulation  effects 
last  for  some  time,  it  is  usually  found  that  when  the  pulse  from  the  brain  at  any 
given  level  in  the  earlier  part  of  the  reaction  is  compared  with  that  from  a  similar 
level  of  volume  in  the  later  part  of  the  reaction,  the  pulse  in  tihe  later  part  is 
larger  than  that  in  the  earlier  part.  This  statement  applies  both  to  the  records 
from  the  sitting-up  position  published  in  the  previous  work  referred  to  above, 
and  to  those  from  the  lying-down  position  published  in  the  present  work. 

With  minor  variations  according  to  the  type  of  restriction,  all  forms  of  cessa- 


38  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

tion  of  breathing  resulted  in  a  constriction  of  the  hand,  and  a  rise  of  volume  of 
the  brain  with  larger  pulse  beginning  the  equivalent  in  time  of  two  to  three 
breaths  after  breathing  is  stopped,  and  reaching  its  height  two  to  four  breaths 
after  breathing  returns.  Increased  depth  of  breathing  and  artificial  snoring  tend 
to  give  a  fall  of  volume  of  the  brain  with  smaller  pulse  and  larger  breathing- 
wave  in  the  volume,  which  condition  remains  throughout  the  period  of  special 
breathing. 

There  are  very  definite  indications  that  the  circulation  change  lags  behind  the 
mental  process.  This  was  shown  in  about  twenty-five  out  of  thirty  tests ;  in  the 
others  the  curve  had  reached  or  approached  the  waking  condition  before  the 
subject  signaled  that  he  was  awake. 

In  all  this  work  I  have  spoken  very  little  of  the  changes  in  the  hand  and  foot. 
This  is  partly  because  fewer  results  were  taken  from  these  than  from  the  brain ; 
partly  because  movement  more  often  obscured  those  that  were  taken;  partly 
because  no  constant  reaction  was  obtained.  Sometimes  the  hand  increased  as 
the  individual  went  to  sleep,  but  usually  fell  nearly  or  quite  to  the  waking  condi- 
tion again,  before  the  brain  had  reached  its  height.  Sometimes  there  was  no 
significant  reaction  in  the  hand  with  going  to  sleep,  and  it  might  even  be  decreased. 
All  stimuli  and  all  awakenings  caused  a  constriction  of  the  hand,  but  these  con- 
strictions were  in  part,  at  least,  only  temporary.  So  far  as  any  conclusion  can  be 
drawn,  it  is  that  there  is  no  rule  in  regard  to  the  volume  of  the  periphery  in  sleep. 
It  would  be  desirable  to  study  this  question  carefully  by  means  of  the  finger 
plethysmograph  which  records  more  accurately  the  local  vaso-motor  changes. 

With  oncoming  of  sleep,  the  most  characteristic  change  in  breathing  is  decrease 
in  amplitude  of  the  abdominal  movements  and  relative  increase  in  the  chest,  com- 
bined with  the  fact  that  the  sleeper  tends  strongly  to  pull  his  head  towards  his 
body  in  inspiration  and  push  it  from  his  body  in  expiration  During  sleep  there 
are  three  types  of  breathing,  with  various  intermediate  forms.  First,  a  period  of 
shallow,  slow  breathing,  usually,  but  not  always,  with  heavy  snoring,  alternating 
with  a  period  of  deeper,  freer,  and  more  rapid  breathing,  which  begins  abruptly ; 
this  alternation  shows  in  both  chest  and  abdomen  Second,  a  regular  breathing 
intermediate  between  the  extremes  of  the  first  type,  but  with  the  chest  (perhaps 
the  total)  movement  deeper  than  in  the  previous  waking  condition,  and  with 
regular  snoring  which  produces  a  sort  of  halt  or  plateau  on  the  inspiratory  part 
of  the  curve  The  artificial  snoring  spoken  of  above  differed  from  this  in  that 
the  resistance  was  there  mainly  at  the  beginning  of  inspiration.  Third,  deep, 
regular  breathing  without  particular  snoring.  In  nearly  all  curves  of  this  type 
there  was  some  evidence  of  a  somewhat  irregular  alternation  of  periods  of  deeper 
with  periods  of  shallower  breathing,  but  no  definite  change  in  rate.  While  in  the 
first  type  the  period  of  deep  breathing  begins  rather  abruptly,  in  the  third  there 
is  a  gradual  transition  from  one  to  the  other.  Sleep  most  often  began  with  the 
first  type,  which  then,  in  the  majority  of  experiments,  gave  place  to  the  second 
or  third  type. 

Stimuli  during  the  first  two  types  gave  an  increased  amplitude,  usually  with 


VOLUME  OF  THE   BRAIN  AND   OF  THE   PERIPHERY  39 

faster,  sometimes  with  slower  rate,  always  with  relative  increase  in  the  abdominal 
movements.  Stimuli  during  the  third  type  usually  gave  a  period  of  shallower  and 
■faster  movements,  which  with  stronger  stimuli  was  followed  by  a  period  of 
increase.  Stimuli  rarely  gave  no  breathing  change  even  with  a  quite  marked 
reaction  in  the  circulation  record.  Awakening  began  with  the  same  effects  as 
stimuli;  and  as  the  subject  became  thoroughly  awake,  the  abdominal  movements 
became  greater,  the  chest  less  than  during  sleep,  with  the  rate  sometimes  decreased, 
more  often  increased. 

There  is  a  very  prominent  breathing  wave  in  the  curves  from  the  hand  and 
brain  during  sleep,  particularly  in  that  from  the  brain.  It  is  diminished  with 
reactions  to  stimuli  and  at  awakening.  This  wave  is  greater  with  snoring  than 
without.  With  snoring  it  is  much  greater  than  that  with  artificial  snoring  when 
awake.  Without  snoring  it  is  often  greater  than  similar  deep  breathing  awake. 
These  statements  are  particularly  true  when  the  first  form  of  brain  plethysmograph 
is  used. 

There  is  an  undulation  in  both  brain  and  hand  curves  covering  several  breaths, 
which  we  shall  call  the  Traube-Hering  wave,  although  possibly  it  should  be  called 
the  Mayer  wave.  This  gives  place  to  a  wave  which  is  usually  larger  and  longer 
during  sleep,  whether  with  a  change  from  passive  to  active  or  not,  only  the  blood- 
pressure  measurements  which  we  shall  study  later  can  make  sure.  As  a  rule,  these 
waves  nearly  correspond  in  the  brain  and  hand  curves,  they  differ  from  each  other 
by  no  more  than  two  or  three  pulse-beats ;  but  they  often  differ  widely  in  relative 
size,  and  at  times,  particularly  when  the  subject  is  going  to  sleep,  some  of  the 
waves  may  be  at  nearly  opposite  phases  in  the  two  records.  During  sleep,  any 
periodic  fluctuation  of  breathing  is  to  be  correlated  with  the  wave  in  the  circula- 
tory record.  The  deeper  breathing  corresponds  to  a  fall  and  trough  of  volume, 
the  more  shallow  to  a  rise  and  crest.  In  the  abrupt  transition  from  restricted  to 
freer  breathing  of  the  first  type,  the  change  to  deep  breathing  is  very  nearly 
simultaneous  with  the  beginning  of  the  fall  of  volume,  most  often  a  couple  of 
pulse-beats  before  it,  sometimes  even  as  much  after  it. 


CHAPTER   III 

THE  BLOOD  PRESSURE 

Method 

At  first  an  attempt  was  made  to  use  the  Mosso  sphygmomanometer  to  measure 
the  variations  of  blood-pressure  during  sleep.  The  result  was  a  failure.  It  is 
impossible  to  estimate  the  blood-pressure  by  compression  of  vessels  that  may 
actively  relax  or  constrict  from  test  to  test.  Furthermore,  the  instrument  and 
position  are  altogether  too  uncomfortable  for  work  on  sleep. 

The  apparatus  finally  used  was  as  follows.  A  sleeve  (Riva-Rocci  or  Erlanger) 
was  fastened  around  the  left  arm  above  the  elbow.  The  Riva-Rocci  sleeve  was 
used  in  the  first  experiments,  the  Erlanger  in  the  later  ones.  The  mercury  manom- 
eter was  placed  on  the  table  in  the  operator's  room,  and  connected  to  the  sleeve 
by  a  thick-walled  rubber  tube.  A  light  weight  plethysmographic  bulb  was  then 
bandaged  firmly  on  the  left  wrist  over  the  radial  artery  and  connected  to  a 
medium  piston  recorder.  In  some  cases  a  medium  weight  bulb  was  also  bandaged 
on  the  flexion  side  of  the  lower  arm  just  below  the  elbow,  and  connected  to  a 
second  recorder. 

To  prevent  bending  of  the  wrist  from  interfering  with  the  bulbs,  a  thin  board 
was  laid  along  the  back  of  the  hand  and  arm,  and  straps  fastened  to  the  board 
were  buckled  lightly  around  the  hand  and  arm. 

In  order  to  make  use  of  the  criteria  of  Erlanger,  the  apparatus  was  further 
complicated  in  the  later  experiments.  A  shallow  cup  with  outlet  to  the  side  was 
covered  with  several  thicknesses  of  rubber-dam,  and  then  fastened  firmly  to  the 
operator's  table.  A  three-way  glass  tube  was  inserted  into  the  rubber  tube 
between  the  manometer  and  the  sleeve.  The  third  branch  of  this  was  connected 
by  a  rubber  tube  to  the  outlet  of  the  cup.  Consequently,  when  the  pressure  was 
raised  in  the  manometer  system,  the  rubber  covering  the  cup  was  bulged  out  into 
an  oval  shape  and  showed  all  variations,  including  the  pulse,  in  the  sleeve.  A 
second  shallow  cup  was  covered  with  a  single  layer  of  rubber-dam.  A  rod  pro- 
jected from  the  bottom  of  this  cup  and  passed  through  a  hole  which  was  cut  in  a 
second  rod  and  provided  with  a  set  screw.  When  this  second  rod  was  clamped 
above  the  first  cup,  therefore,  the  second  cup  could  be  moved  downward  until  the 
two  rubber  coverings  fit  firmly  together  and  any  change  in  the  one  would  cause  a 
corresponding  change  in  the  other.  The  cavity  of  the  second  cup  was  then 
connected  to  a  piston-recorder,  which  consequently  recorded  all  changes  of 
pressure,  including  the  pulse,  in  the  manometer  system.  The  breathing  and  the 
brain  volume  were  always  recorded  along  with  the  blood-pressure  tracings.  The 
first  form  of  brain  plethysmograph  was  used  in  all  cases  for  the  brain  volume. 

40 


THE   BLOOD    PRESSURE  4^ 

It  was  found  that  movements  of  the  subject,  especially  the  breathing  move- 
ments, almost  invariably  caused  a  slight  movement  of  the  arm,  and  this  gave  a 
fluctuation  in  the  curve  from  the  wrist  or  lower  arm.  To  avoid  this,  a  swing  was 
suspended  from  the  ceiling  by  a  single  strand,  like  that  used  in  the  work  on  the 
brain  volume.  When  this  was  hung  about  an  inch  above  the  bed,  and  the 
subject's  arm  was  placed  in  it,  practically  all  effects  of  movement  except  the 
contractions  of  the  arm  muscles  themselves  were  eliminated. 

Before  the  apparatus  for  the  study  of  blood  pressure  was  completed,  the  first 
subject  moved  out  of  town.  All  the  results  of  this  kind  were  then  obtained  from 
the  second  subject,  except  a  few  special  records  which  were  taken  from  other 
normal  subjects. 

Results 

I  can  best  show  the  nature  of  the  work  by  describing  a  few  typical  records. 
The  kymograph  was  rotated  rapidly,  so  that  the  length  of  paper  occupied  by  each 
test  was  usually  several  feet.  On  this  account  it  will  be  necessary  to  reduce  the 
tracings  considerably  in  the  reproduction.  Unless  otherwise  stated,  the  diameter 
will  be  multiplied  by  one-half. 

July  2j,  III,  no.  I  (Fig.  43,  Plate  40)  and  no.  2  (Fig.  44,  Plate  41). — These 
are  extracts  from  a  very  long  record.  A  few  inches  in  the  beginning  and  a  por- 
tion in  the  middle  are  omitted,  since  they  show  no  additional  point.  The  curves 
from  the  top  down  are  the  abdominal  breathing,  the  chest  breathing,  the  indicator 
line,  a  curve  from  the  lower  arm,  the  brain  volume,  and  the  tracing  from  the 
sleeve.  The  Erlanger  sleeve  was  used.  The  signals  on  the  indicator  line  were 
made  by  the  operator,  and  the  adjacent  numbers  show  the  pressure  at  that  instant. 
The  air  had  been  pumped  into  the  manometer  system  just  before  no.  i  began. 
The  subject  had  been  asleep  and  the  oncoming  of  the  pressure  had  disturbed  but 
had  not  awakened  him.  It  will  be  seen  that  throughout  no.  i  and  the  first  part 
of  no.  2,  the  tracing  from  the  lower  arm  fell  gradually  with  a  slight  breathing-wave 
in  it,  and  had  to  be  raised  artificially  at  times.  All  abrupt  rises  and  falls  in  this, 
and  abrupt  rises  in  the  curve  from  the  sleeve  are  artificial.  At  a,  the  air  was 
allowed  to  escape  rapidly  for  a  moment,  resulting  in  a  quick  fall  in  the  sleeve 
curve.  At  c,  the  escape  was  opened  somewhat  more.  It  will  be  observed  that  the 
fall  in  the  tracing  from  the  lower  arm  is  not  influenced  by  the  irregularities  in  the 
sleeve  record.  At  h,  d,  e,  f,  g,  h,  i,  j,  k,  I,  m,  n,  and  some  other  places,  the  drums 
were  stopped  and  lines  of  reference  were  struck  in  all  records.  At  0,  the  fall  in 
the  brain  volume  was  accompanied  by  a  rise  in  the  curve  from  the  lower  arm  with 
some  evidence  of  pulse,  and  the  arm  curve  was  dropped  artificially.  At  p,  the 
brain  volume  reached  another  crest,  and  the  curve  from  the  arm  forms  an  arch 
which  spans  the  trough  in  the  brain  record.  The  fall  in  brain  volume  after  p  was 
accompanied  by  another  rise  in  the  arm  tracing  with  some  pulse.  At  q,  there 
was  a  slight  secondary  crest  in  the  brain  and  a  similar  trough  in  the  arm.  The 
arm  volume  continued  to  increase,  so  that  p,  at  which  the  pressure  was  about 
no  mm.,  was  the  beginning  of  a  permanent  rise  and  the  returning  pulse.     At 


42  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

several  other  places,  notably  r,  s,  and  t,  a  fall  in  the  brain  was  accompanied  by  a 
relatively  rapid  rise  in  the  arm  curve,  with  larger  pulse  during  the  rise  in  the 
arm.  The  rise  in  the  arm  may  begin  one  or  two  pulse-'beats  before  the  fall  in  the 
brain.  The  more  rapid  the  rise,  the  larger  the  pulse  in  the  arm.  It  will  be 
seen  that  the  pulse  in  the  arm  is  regularly  of  the  nature  of  a  simple  step-up  in 
volume,  and  it  is  only  just  at  the  last  of  the  record  that  the  end  of  the  pulse  wave 
begins  to  fall  below  its  crest. 

Three  forms  of  pulse  with  intermediate  stages  may  be  distinguished  in  the 
curve  from  the  sleeve.  In  the  first,  the  rise  is  sudden  and  the  fall  with  small 
waves  is  gradual  from  the  crest  to  the  end  of  the  pulse.  In  the  second  there  is  a 
greater  rise  and  quick  fall  in  the  first  part  of  the  pulse-wave.  The  dicrotic  and 
the  latter  part  of  the  wave  are  relatively  lower.  The  third  is  characterized  by 
the  more  elevated  dicrotic  and  normal  pulse  form.  Towards  the  end  of  the 
record,  it  will  be  seen  that,  in  spite  of  the  slowly  escaping  air,  the  sleeve  was 
actually  lifted  and  held  up  by  the  returning  blood,  and  the  pressure  increased 
from  103  mm.  to  105  mm.  The  greater  the  returning  pulse  in  the  arm,  the  more 
the  pulse  form  approached  the  third  type ;  but  the  most  definite  appearance  of  the 
third  type  occurred  at  the  time  of  elevation  of  the  sleeve. 

At  several  places  a  respiratory  wave  shows  in  the  pressure  curve.  There  are 
two  very  clearly  just  before  h.  The  pulse  is  found  mainly  on  the  rise  of  the 
wave.  This  rise  begins  in  the  expiration  and  near  the  crest  of  the  respiratory 
wave  in  the  brain  volume. 

H.,  July  2J,  II  (Fig.  45,  Plate  42). — In  the  record  described  above,  the  paper 
was  not  long  enough  to  show  the  last  of  the  test  fully.  This  extract  is  reproduced 
to  illustrate  the  usual  condition  at  the  end.  The  subject  was  asleep  except  that 
the  stimulus  of  the  experiment  disturbed  him.  The  pressure  had  been  on,  and 
the  arm  volume  had  been  sinking  through  three  feet  of  record  omitted  at  the 
beginning.  The  pulse  from  the  sleeve  had  changed  from  the  first  type  to  an 
imperfect  second  type.  At  a,  a  short  fall  in  the  brain  was  accompanied  by  a 
slight  rise  in  the  arm  curve.  From  112  mm.  to  loi  mm.  the  pressure  was  allowed 
to  fall  rapidly.  The  arm  curve  began  to  rise  with  small  pulse  at  about  11 1  mm. 
The  returning  blood  lifted  the  sleeve  and  raised  the  pressure  to  102  mm.  The 
pressure  was  abruptly  dropped  to  98.5  mm.  but  the  elevation  of  the  sleeve  again 
raised  it  to  100  mm.  or  more.  The  rise  with  pulse  in  the  arm  can  be  seen  to  be 
greater  with  falling  brain  volume  and  less  with  rising  brain  volume.  Each  pulse 
from  the  arm  is  a  simple  step-up  in  the  curve  until  near  the  end,  after  the  sleeve 
has  been  lifted  considerably,  when  the  end  of  the  wave  drops  below  the  crest  and 
the  pulse  assumes  the  usual  form.  The  rise  in  the  arm  volume  ceases  at  the 
same  place.  The  pulse  from  the  sleeve  becomes  of  the  third  type  with  elevation 
of  the  sleeve. 

The  last  portion  of  this  record  is  especially  typical.  There  is  a  slight  breath- 
ing wave  in  the  arm  record  before  pulse  returns.  Its  relations  are  uncertain. 
But  the  rise  seems  to  begin  on  or  just  before  the  trough  of  volume. 

June  2^,  I  (Fig.  46,  Plate  43). — The  middle  portion  of  this  record  is  repro- 


THE   BLOOD    PRESSURE  43 

duced  in  order  to  show  more  completely  the  variations  in  the  pressure  curve  that 
are  often  found  before  the  permanent  rise  with  the  pulse  begins.  The  curves 
from  the  top  down  are  the  chest  breathing,  the  indicator  line,  the  bulb  on  the  wrist, 
and  the  brain  volume.  The  pressure  had  been  on  and  the  wrist  tracing  had  been 
sinking  through  two  feet  of  record.  The  subject  was  asleep,  at  least  lightly.  At 
a,  b,  c,  d,  and  e,  the  drums  were  stopped  and  lines  of  reference  were  struck.  The 
brain  volume  showed  a  disturbance,  a  fall  with  smaller  pulse  at  several  places. 
A  fall  in  the  brain  volume  was  accompanied  by  a  rise  in  the  curve  from  the  wrist ; 
a  trough  in  the  brain  record  corresponded  to  a  crest  in  the  record  from  the  wrist. 
The  amount  of  change  in  the  two  is  fairly  proportional.  The  change  in  the  wrist 
curve  may  begin  one  or  two  pulse-beats  before  the  change  in  the  brain.  The 
permanent  rise  with  pulse  began  at  about  115  mm.  The  more  rapid  the  rise 
the  greater  the  pulse,  and  a  more  rapid  rise  corresponds  in  general  to  a  fall  in  the 
brain.  In  the  latter  part  of  the  record,  which  is  not  reproduced,  the  rise  in  the 
arm  continued  until  the  pulse  assumed  its  full  form  as  in  the  above  descriptions. 
It  should  be  emphasized  that  fluctuations  in  the  pressure  curve  corresponding  to 
changes  in  the  brain  occur  before  a  pulse  has  shown  itself  in  the  pressure  curve. 
In  this  respect  this  record  is  typical  of  many  others. 

The  rise  in  the  small  respiratory  wave  in  the  wrist  tracing  begins  during  the 
rise  of  brain  volume,  sometimes  near  its  crest. 

May  4,  III,  Test  i  (Fig.  47,  Plate  43). — The  diameter  was  multiplied  by 
three-fourths.  The  pressure  had  been  on  only  a  short  time  when  this  extract 
began.  The  subect  was  sleeping  lightly.  The  curves  in  order  from  the  top  are 
the  abdominal  breathing,  the  chest  breathing,  the  indicator  line,  the  brain  volume, 
and  the  wrist  (radial).  At  a,  the  subject  was  disturbed,  the  abdominal  breathing 
increased  and  there  was  some  movement.  The  brain  volume  fell  with  smaller 
pulse.  The  curve  from  the  wrist  rose  with  some  evidence  of  pulse.  This  reaction 
was  followed  by  a  period  of  restricted  breathing  and  rising  brain  volume,  the 
wrist  curve  turned  downward  and  the  pulse  disappeared  from  it.  The  permanent 
rise  began  at  about  145  mm.,  although  there  is  little  evidence  of  pulse  until  143.5 
mm.  At  b,  lines  of  reference  were  struck.  Just  afterward  there  was  another 
disturbance  with  increased  abdominal  breathing  and  falling  brain  volume.  At  the 
same  time  the  curve  from  the  wrist  showed  a  great  acceleration  in  its  rise.  Then 
followed  a  period  of  restricted  breathing,  rising  brain  volume  and  slower  rise  in 
the  wrist.  After  the  portion  reproduced,  the  rise  in  the  arm  continued  until  the 
return  of  the  fully  formed  pulse.  The  Riva-Rocci  sleeve  was  used  in  this  test 
and  in  all  others  that  show  similarly  high  readings  with  this  subject.  It  will  be 
seen  that  there  is  a  small  breathing  wave  in  the  wrist  tracing.  Measurement 
shows  that  the  rise  in  this  begins  just  before  the  crest  of  the  breathing  wave  in  the 
brain  volume  and  in  the  beginning  of  expiration.  A  quick  pulse  followed  by  a 
delayed  one  obscures  the  form  of  the  curve  in  several  places. 

May  16, 1  (Fig.  48,  Plate  44). — The  pressure  had  been  on  and  the  wrist  curve 
had  been  sinking  with  shallow  waves  through  three  feet  of  record  when  this 
extract  began.     Periods  of  sleep  with   restricted  breathing  and  some  snoring 


44  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

alternated  with  periods  of  deeper,  freer  breathing.  As  usual  the  restricted  breath- 
ing was  accompanied  by  a  rising  brain  volume,  the  freer  breathing  by  a  falling 
brain  volume.  Corresponding  to  the  fall  in  the  brain,  there  was  a  rapid  rise  in 
the  tracing  from  the  wrist  with  marked  pulse.  Corresponding  to  the  rising  brain 
volume,  there  was  a  slower  rise  in  the  wrist  curve,  or  none  at  all,  with  little  or  no 
pulse.  There  were  four  periods  of  this  kind  during  the  extract.  Under  these 
circumstances  it  is  difficult  to  place  exactly  the  beginning  of  the  permanent  rise 
which  represents  the  average  blood  pressure  at  the  moment.  It  was  counted  at 
127  -\-  mm.  Lines  of  reference  were  struck  at  the  end.  Measurements  from 
these  showed  that  each  accelerated  rise  in  the  wrist  curve  began  a  little  before 
the  fall  in  the  brain,  and  the  increase  in  breathing  began,  if  anything,  before  the 
rise  in  the  wrist. 

May  16,  II  (Fig.  49,  Plate  43). — The  wrist  curve  had  been  sinking  through 
about  two  feet  of  record.  This  extract  also  shows  an  alternation  of  restricted 
breathing  and  rising  brain  volume  with  increased,  freer  breathing  and  falling 
brain  volume.  But  there  were  in  addition  several  shorter  waves  in  the  brain 
without  corresponding  definite  breathing  changes.  The  fall  in  brain  volume  again 
accompanies  a  rise  in  pressure.  Lines  of  reference  were  struck  at  a  and  b.  In 
reproducing,  the  engraver  painted  out  the  reference  line  under  a,  in  the  pressure 
curve.  In  attempting  to  restore  it,  he  placed  it  too  far  forward  and  deformed 
the  curve  somewhat.  Measuring  from  these  it  is  found  that  the  rise  in  pressure 
began  a  little  before  the  fall  in  brain  volume  in  two  cases,  a  little  afterward  in 
two  cases  and  nearly  simultaneously  in  the  other  cases.  The  breathing  change 
just  after  a  was  slightly  delayed,  the  others  began  a  little  before  the  change  in 
pressure.  In  few  records  was  it  as  difficult  as  in  this  one  to  determine  an  average 
point  of  permanent  rise.  It  was  taken  as  15 1.5  mm.  A  few  inches  after  the 
close  of  the  portion  reproduced  the  subject  entirely  awakened  with  considerable 
movement,  and  the  full  pulse  form  soon  returned. 

May  30,  I  (Fig.  50,  Plate  45). — The  brain  curve  is  imperfect  in  this  record 
because  of  trouble  with  the  recorder;  but  it  is  still  adequate  to  show  the  changes 
of  volume.  The  subject  was  asleep.  This  extract  is  reproduced  to  illustrate 
more  completely  the  effect  of  disturbance  followed  by  return  to  sleep.  The  brain 
tracing  had  been  raised  artificially  and  a  slight  rise  in  the  pressure  curve  had 
begun  while  the  subject  was  still  snoring.  At  a  the  snoring  ceased  and  the 
subject  was  much  disturbed.  The  brain  curve  fell  and  had  to  be  raised.  The 
wrist  (radial)  curve  rose  rapidly  with  pulse.  Then  the  subject  began  to  rest 
again,  the  brain  volume  rose,  the  pressure  curve  lost  its  pulse  wave,  rose  more 
slowly,  and  then  fell.  Just  before  c  another  rise  in  the  pressure  tracing  with 
falling  brain  volume  began.  The  permanent  rise  was  taken  as  iii  mm.,  which 
was  still  5.5  mm.  less  than  the  records  taken  while  awake  the  same  night.  Lines 
of  reference  were  struck  at  b  and  c. 

There  is  a  respiratory  wave  in  the  wrist  curve.  The  rise  begins  in  the 
expiration. 

May  3,  II  (Fig.  51,  Plate  46). — This  is  a  short  extract  which  is  reproduced  in 


THE   BLOOD    PRESSURE  45 

order  to  show  better  how  the  breathing  wave  may  influence  the  pulse  in  the 
pressure  curve.  Each  wave  usually  begins  with  a  small  pulse  followed  by  one  or 
two  larger  ones  on  the  rise,  while  on  the  fall,  the  pulse  is  absent  or  much  smaller. 
Measurement  from  lines  of  reference  at  the  end  of  the  test  (not  reproduced) 
showed  that  the  rise  with  pulse  in  the  pressure  record  begins  on  the  rise  of  the 
breathing  wave  in  the  brain.  A  slip  of  the  paper  at  x  serves  as  an  approximate 
reference  line.  The  pressure  wave  is  at  least  a  pulse-beat  later  than  the  cor- 
responding wave  in  the  brain.  The  subject  was  asleep.  The  diameter  was  multi- 
plied by  three-fourths. 

May  4,  I.  Test  2  (Fig.  52,  Plate  47). — The  subject  was  nearly  awake.  The 
tracings  from  the  top  down  are  abdominal  breathing,  chest  breathing,  indicator 
line,  brain  volume,  and  curve  (pressure)  from  the  wrist.  The  pressure  had  been 
thrown  on  while  the  drum  was  stopped  at  a.  This  disturbed  the  subject.  At  h, 
occurred  a  period  of  restricted  breathing  and  rising  brain  volume  accompanied  by  a 
falling  pressure  curve  with  no  pulse.  At  c,  began  increased  breathing,  falling  brain 
volume  and  rising  pressure  tracing  with  pulse.  This  was  the  permanent  rise, 
which  therefore  began  at  146  mm.  There  is  a  considerable  respiratory  wave  in 
both  brain  and  pressure  curves.  There  is  a  noticeable  pulse  on  the  rise  of  the 
pressure  tracing,  little  or  none  on  the  fall.  The  rise  of  pressure  begins  near  the 
crest  of  the  volume  wave  during  expiration.  The  crest  of  pressure  occurs  not  far 
from  the  trough  of  volume,  during  inspiration.  A  given  phase  of  pressure  occurs 
rather  before  than  after  the  opposite  phase  of  volume. 

The  extract  is  reproduced  in  the  original  size. 

July  22,  VI  (Fig.  53,  Plate  48). — This  is  reproduced  for  comparison  with 
July  27,  II  (Fig.  45,  Plate  42)  and  III  (Figs.  43  and  44,  Plates  40  and  41).  It 
is  an  extract  showing  the  beginning  of  the  permanent  rise  and  pulse.  The  brain 
plethysmograph  was  adjusted  to  show  a  better  pulse.  The  subject  was  awake 
but  drowsy.  At  a,  b,  d,  and  e,  lines  of  reference  were  struck  by  stopping  the 
drum  a  moment.  There  are  several  artificial  changes  in  the  pressure  and  sleeve 
curves.  At  c,  the  tracings  were  somewhat  confused  by  movements  of  the  subject. 
The  permanent  rise  with  some  pulse  began  about  118  mm.  and  became  more 
definite  at  115.5  mm.  At  several  places,  notably  following  d  and  e,  a  fall  in  the 
brain  volume  was  accompanied  by  a  rise,  or  more  rapid  rise,  in  the  pressure  curve, 
with  emphasized  pulse.  The  effect  in  the  pressure  may  precede  the  brain  reaction 
one  or  two  pulse-beats.  A  higher  position  of  the  dicrotic  in  the  sleeve  curve 
answers  to  an  increase  in  the  pressure  tracing,  but  the  change  in  the  sleeve  curve 
cannot  be  determined  with  so  much  certainty. 

July  13,  III  (Fig.  54,  Plate  49). — The  subject  was  awake,  but  very  drowsy. 
The  curves  from  the  top  down  are  the  abdominal  breathing,  chest  breathing, 
indicator  line,  wrist,  brain  volume,  and  lower  arm.  Lines  of  reference  were 
struck  at  a,  c,  d,  and  e.  The  pressure  was  not  on  at  first,  and  it  will  be  seen  that 
the  undulations  in  the  curve  from  the  wrist  were  very  nearly  parallel  with  those 
in  the  brain  volume.  The  curve  from  the  lower  arm  follows  a  similar  course, 
but  the  correspondence  is  not  always  so  exact.     In  such  respects  this  record  is 


46  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

especially  typical.  At  b,  the  pressure  was  thrown  on.  Following  this,  the  brain 
volume  showed  several  undulations  of  different  lengths.  In  each  case  the  rise  in 
the  pressure  curve  corresponds  to  a  fall  of  brain  volume,  the  pressure  curve 
forms  an  arch  answering  to  a  trough  in  the  brain  record.  The  change  in  the 
pressure  record  may  be  delayed  slightly,  not  more  than  a  pulse-beat.  The  tracing 
from  the  lower  arm  changes  in  the  same  direction  as  that  from  the  wrist,  but  the 
reaction  is  always  the  larger  in  the  lower  arm.  In  large  changes  like  that  at  /, 
it  is  of  course  necessary  to  reduce  to  the  recorder  level,  in  order  to  determine  the 
phasic  relation. 

The  last  part  of  this  record  was  run  alternately  slowly  and  rapidly  in  order 
to  study  pulse  form,  and  is,  on  that  account,  not  reproduced  here. 

B.,  June  21  (Fig.  55,  Plate  50). — The  diameter  is  multiplied  by  three-fourths. 
Several  blood  pressure  records  were  taken  from  other  subjects  while  awake,  in 
order  to  study  the  technique  of  the  method,  the  relations  of  the  Traube-Hering 
wave,  and  other  matters.  This  is  an  extract  out  of  a  record  from  a  strongly 
built  man  B.,  whose  blood  pressure  was  about  30  mm.  higher  than  that  of  the 
second  trephined  subject.  Since  it  was  of  course  impossible  to  obtain  a  brain 
tracing,  a  curve  was  taken  from  the  right  hand,  while  the  left  arm  was  used  with 
the  blood  pressure  apparatus. 

The  blood  had  begun  to  return  at  145  mm.  and  the  present  extract  represents 
the  condition  after  5  mm.  more  of  fall.  The  curves  from  the  top  down  are  the 
chest  breathing,  the  indicator  line,  the  wrist  tracing  and  the  plethysmographic 
curve  from  the  right  hand.  Lines  of  reference  were  struck  at  a  and  h.  Measure- 
ment shows  that  the  undulations  in  the  pressure  record  parallel  almost  exactly 
those  in  the  hand  volume.  A  rise  with  pulse  in  the  pressure  corresponds  to  a 
rise  of  hand  volume,  a  fall  of  pressure  corresponds  to  a  fall  of  volume.  The 
largest  pulse  in  the  pressure  tracing  is  always  at  the  crest  of  the  wave,  or  on  the 
rise  and  crest.     This  extract  is  typical  of  all  tests  with  the  subject  B. 

W .,  July  II  (Fig.  56,  Plate  50). — This  extract  is  reproduced  full  size.  It  is 
from  another  subject  W.  It  was  taken  to  show  the  effect  of  sudden  changes  of 
pressure  in  the  sleeve.  The  curves  from  the  top  down  are  the  chest  breathing, 
the  indicator  line,  the  volume  of  the  lower  arm,  the  volume  of  the  wrist,  and  the 
sleeve  record.  The  question  was  whether  the  gradual  fall  which  is  always  found 
after  the  pressure  is  thrown  on,  could  be  in  any  way  influenced  by  or  due  to 
change  of  pressure  in  the  sleeve.  A  breathing  wave  shows  in  the  arm  curve,  very 
slightly  in  the  wrist.  At  the  mark,  the  pressure  was  suddenly  raised  in  the 
manometer  system  by  pressing  the  inflator,  and,  after  a  few  pulse-beats,  was  as 
suddenly  released.  There  was  no  noticeable  effect  upon  the  wrist  or  arm  curves ; 
both  continued  their  descent  without  interruption. 

Summary 
The  net  result  of  the  study  of  blood  pressure  is  as  follows.     After  the  pressure 
is  thrown  on,  there  is  a  gradual  fall  in  the  volume  of  the  wrist  and  the  lower 


THE   BLOOD    PRESSURE  47 

arm,  and,  I  may  add,  three  curves  taken  from  the  hand  showed  the  same  result. 
There  is,  then,  a  general  decrease  in  volume  which  signifies  an  escape  of  blood 
from  the  member  below  the  sleeve.  This  decrease  cannot  be  due  to  the  release 
of  pressure  in  the  sleeve,  since  it  is  not  influenced  by  a  rise  or  fall  amounting  to 
several  millimeters  in  that  pressure.  Even  before  the  pressure  in  the  sleeve  has 
fallen  to  the  point  at  which  a  pulse  returns  in  the  occluded  portion,  a  wave  may 
be  found  in  the  pressure  tracing  which  checks  the  fall  or  causes  a  rise  in  the 
tracing.  Records  taken  simultaneously  from  the  wrist  and  lower  arm  or  wrist 
and  hand  show  that  this  wave  is  parallel  throughout  the  occluded  portion  and 
therefore  cannot  originate  within  that  portion.  Waves  from  the  wrist  and  lower 
arm  are  more  absolutely  parallel  to  each  other  than  before  the  pressure  was 
applied.  But  all  reactions  are  more  emphasized  in  the  lower  arm  than  in  the 
wrist.  Furthermore  the  wave  is  too  regular  to  be  in  any  way  probably  due  to 
movement.  We  may  infer  that  it  is  caused  by  a  wave  in  the  general  blood- 
pressure  and  that  blood  is  getting  through  below  the  sleeve.  This  blood-pressure 
wave  is  related  to  the  wave  (Traube-Hering)  in  the  volume  record  (brain  or  other 
hand)  taken  at  the  same  time. 

When  the  fall  in  the  sleeve  pressure  has  reached  a  certain  point,  a  rise  shows 
itself  in  the  curve  from  the  occluded  portion,  and  at  the  same  time  or  soon  after- 
wards, a  pulse  begins  in  the  same  curve.  Both  may  be  visible  in  the  lower  arm 
somewhat  before  they  are  in  the  wrist.  The  appearance  of  pulse  never  delayed 
more  than  three  millimeters  after  the  beginning  of  the  rise,  and  the  two  were  more 
often  practically  simultaneous.  When  there  were  fluctuations,  as  was  usually  the 
case,  the  pulse  was  present  or  emphasized  on  the  rise  of  the  wave  and  tended  to 
disappear  on  the  fall.  This  wave  corresponds  to  the  earlier  wave  in  the  pressure 
tracing  except  that,  measured  by  its  phasic  relation  to  the  simultaneous  volume 
changes,  it  seems  to  show  itself  a  little  more  quickly,  perhaps  as  much  as  two 
pulse-beats.  Such  a  relation  to  pulse  makes  certain  the  conclusion  that  the 
fluctuation  is  due  to  blood  pressure  changes.  Furthermore,  the  phasic  relation  of 
the  wave  in  the  curve  from  the  occluded  portion  to  that  in  the  volume  of  brain 
or  hand  is  the  same  with  all  variations  in  length  of  wave.  This  shows  that  there 
is  no  appreciable  delay  in  the  expression  of  the  blood  pressure  change  in  the 
tracing. 

After  an  additional  fall  of  three  to  ten  millimeters  (the  average  was  six  and 
one-half  millimeters)  in  the  sleeve  pressure,  the  sleeve  curve  began  to  rise  and 
the  pressure  in  it  was  increased  one  to  three  millimeters.  This  was  without  doubt 
due  to  elevation  of  the  sleeve  by  the  returning  blood.  The  exact  point  at  which 
it  occurred,  seemed  to  depend  not  merely  on  the  amount  of  fall  in  pressure  but 
also  upon  the  time  allowed  for  blood  to  accumulate  in  the  portion  below  the  sleeve. 
Iin  some  cases,  disturbance  of  the  subject  by  the  returning  circulation  hastened  it. 
But  the  elevation  did  not  show  itself  until  enough  blood  had  accumulated  in  the 
occluded  portion  to  sustain  the  sleeve.  Such  an  elevation  might  be  of  some 
importance  in  a  method  of  "  staircase-curves." 

With  the  lifting  of  the  sleeve,  the  rise  of  volume  in  the  occluded  portion 


48  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

became  less  and  soon  ceased.  The  pulse  from  the  wrist  and  lower  arm  was, 
during  the  rise  in  these  curves,  a  simple  step-up  in  volume.  As  the  sleeve  rose, 
and  the  volume  of  the  occluded  portion  stopped  its  rise,  this  pulse  assumed  a 
more  normal  form.  Three  forms  of  pulse  were  found  in  the  sleeve  curve.  There 
was  increase  in  size  and  elevation  of  the  dicrotic  in  the  sleeve  pulse  with  the 
returning  blood,  especially  with  the  lifting  of  the  sleeve. 

Using  the  rise  in  volume  of  the  occluded  portion,  especially  when  accompanied 
by  pulse,  as  the  criterion  of  pressure,  the  records  show  the  following  facts.  The 
blood  pressure  was  several  millimeters  lower  during  sleep  than  during  the  waking 
condition.  The  difference  was  usually  8  to  lo  mm.  But  the  series  (July  27) 
which  seemed  most  satisfactory  from  every  standpoint  at  the  time  gave  only  5  mm. 
On  the  other  hand,  one  series  showed  a  difference  of  17  mm.  I  will  quote  six 
series  in  which  the  subject  slept  well  enough  to  make  a  fairly  accurate  and  con- 
tinuous series  possible.  Each  test  is  enclosed  in  parentheses ;  and  in  each,  the  con- 
dition of  the  subject,  the  point  of  permanent  rise,  and  the  point  of  returning  pulse 
are  stated  in  order,  with  dashes  between.  The  tests  in  each  series  are  given  in  the 
order  in  which  they  were  taken.  But,  since  two  tests  were  sometimes  taken  on  a 
single  paper,  the  number  of  the  test  does  not  always  correspond  to  the  number  of 
the  paper,  which  was  used  for  reference  with  those  reproduced  above.  Series 
April  27  was  (awake — 151.5 — i5i-5),  (asleep — 144- — 144),  (asleep  until  blood 
returned — 141. 5 — i4i-5)  and  (awake — 152 — 152).  Series  May  3  was  (nearly 
asleep — 134 — 131),  (asleep — 131 — 128),  (disturbed  and  moving — 136 — 136), 
(nearly  or  quite  asleep — 126 — 125)  and  (awake — 134.5 — 134-5).  Series  May  4 
was  (awake — 148.5 — -148.5),  (waked  as  test  began — 146 — 146),  (asleep — 139 — 
136.5),  (asleep — 138 — 136),  (waked  in  test — 145 — 143.5),  (waked  in  test — 143 — 
142),  (asleep — 139 — 139)  and  (awake  but  drowsy — 143 — 141).  Series  May  30 
was  (partly  asleep — in— iii),  (more  deeply  asleep — no — 107)  and  (awake — 
116.5 — 116.5).  Series  July  6  was  (sleeping  lightly,  awakened  in  test — 117 — 114), 
(light  sleep — 115 — 112),  (awakened  as  test  began — 120 — 120),  (asleep — 107 — 
107),  (wakened  and  began  to  move  in  test — 124.5 — 124.5)  and  (awake — 124 — 
124).  Series  July  27  was  (asleep — 113 — no),  (asleep — in — in),  (asleep — 
no — no),  (asleep — 113 — no),  (lightly  asleep — 113 — no),  (awake — 118 — 115) 
and  (awake — 115 — 115).  I  am  unable  to  trace  any  definite  curve  of  sleep  in  the 
pressure,  perhaps  because  of  the  irregular  disturbance  of  the  subject. 

With  the  second  subject  it  is  found  that  the  Traube-Hering  wave  in  the  brain 
volume  is  an  active  process,  both  while  the  subject  is  asleep  and  while  he  is 
awake.  The  fall  of  volume  occurs  during  the  rise  of  pressure,  the  rise  of  volume 
occurs  during  the  fall  of  pressure.  In  the  majority  of  cases  the  rise  of  pressure 
begins  one  or  two  pulse-beats  before  the  fall  of  volume.  Sometimes  it  is  slightly 
delayed.  Since  the  wave  in  the  undisturbed  hand  is  approximately  parallel  to  that 
in  the  brain,  it  is  also  an  active  process.  With  the  subject  B.  the  Traube-Hering 
wave,  in  the  hand  at  least,  is  found  to  be  a  passive  process.  The  volume  rose 
with  rising  pressure  and  fell  with  falling  pressure.  With  the  subject  W.  the  wave 
in  the  hand  is  a  mixture,  sometimes  primarily  active,  sometimes  primarily  passive. 


THE   BLOOD    PRESSURE  49 

It  is,  of  course,  impossible  to  say  with  certainty  whether  these  statements  would 
hold  of  the  brain  if  a  record  could  be  taken. 

Disturbance  during  sleep  invariably  caused  a  rise  of  pressure  with  falling 
brain  volume.  The  rise  of  pressure  sometimes  showed  itself  one  or  two  pulse- 
beats  before  the  fall  of  brain  volume.  Less  often  it  was  slightly  delayed.  Return 
to  sleep,  or  even  drowsing,  was  always  accompanied  by  a  falling  pressure  and  a 
rising  brain  volume. 

A  respiratory  wave  is  found  in  many  of  the  records.  The  relations  are  of 
course  most  certain  after  the  pulse  has  begun  to  return.  There  is  then  no  possi- 
bility of  error,  such  as  there  is  when  the  pressure  in  the  sleeve  is  very  high,  from 
a  delay  in  the  actual  change  in  pressure  showing  itself  in  the  curve.  The  fact 
that  the  pulse-beats  vary  in  length,  especially  when  an  unusually  short  beat  is 
followed  by  an  unusually  long  one,  enables  one  to  identify  the  same  beat  in 
different  curves,  and  to  compare  their  temporal  positions.  It  is  found  that  there 
is  no  important  delay  on  account  of  the  sleeve.  And  since  the  pressure  change 
shows  itself  in  the  change  in  size  of  pulse  breaking  through,  as  well  as  in  the 
change  in  level  of  the  pressure  curve,  we  may  infer  that  there  is  no  appreciable 
delay  in  the  change  in  pressure  showing  itself  in  the  pressure  curve.  The  rise 
with  pulse  in  the  pressure  curve  begins  on  the  rise  of  the  respiratory  wave  in  the 
brain  volume,  the  fall  of  pressure  begins  on  the  fall  of  volume.  Most  often  the 
relation  is  such  that  the  rise  of  pressure  begins  just  before  or  even  sometimes  on 
the  crest  of  volume.  This  is  true  with  slow  breathing  and  long  waves,  where 
delay  would  play  less  part,  as  well  as  with  more  rapid  breathing  and  shorter  waves. 
I  am  not  sure  whether  there  is  a  difference  'between  sleeping  and  waking;  but, 
if  anything,  the  rise  of  pressure  seems  to  begin  earlier  on  the  rise  of  volume 
during  sleep. 

Study  of  the  change  in  size  of  pulse  and  position  of  the  dicrotic  in  the  sleeve 
curve  confirms  the  conclusions  from  the  wrist  and  lower  arm  curves.  But  in  my 
own  records  at  least,  I  can  be  more  certain  of  the  changes  in  the  wrist  and  lower 
arm  than  of  those  in  the  sleeve  curve. 

While  waiting  for  the  subject  to  go  to  sleep,  the  kymograph  was  often  run 
slowly  as  in  the  study  of  volume  changes.  The  results,  therefore,  constitute  addi- 
tional evidence  of  the  changes  in  brain  volume  with  the  second  subject  lying  down 
and  using  the  first  form  of  brain  plethysmograph.  Altogether  there  were  eight 
unambiguous  cases  of  going  to  sleep,  all  of  which  gave  a  rise  of  volume  with 
larger  pulse.  There  were  ten  cases  of  awakening,  all  of  which  caused  a  fall  of 
brain  volume  with  smaller  pulse. 


CHAPTER   IV 

THE   HEART   RATE  AND    PULSE   TRANSMISSION    TIME 

Method 

The  heart  rate  is  so  obviously  a  possible  factor  in  the  circulation  changes  which 
accompany  sleep,  that  it  is  necessary  to  determine  it  accurately.  A  study  of  the 
transmission  time  within  the  arteries  was  added  for  a  dififerent  reason.  All 
methods  of  blood-pressure  measurement,  such  as  the  process  described  in  the 
previous  chapter,  are  subject  to  one  criticism.  They  act  as  a  stimulus  to  the 
subject,  especially  when  applied  to  a  sleeping  individual.  Since  the  rate  of  trans- 
mission of  the  pulse  wave  is  supposedly  influenced  primarily  by  the  tonicity  of 
the  vessels  and  by  the  blood  pressure,  it  was  thought  possible  to  obtain  by  this 
means  some  indication  of  changes  in  sleeping  and  waking,  and  with  reactions 
during  sleep.  The  exact  pressure  could  not  be  given  of  course,  but  the  direction 
of  change  might  be  ascertained;  and  the  taking  of  the  record  does  not  act  as  a 
special  stimulus  to  the  subject. 

To  measure  both  the  heart  rate  and  pulse  transmission  time,  I  recorded  the 
chest  breathing,  the  abdominal  breathing,  the  brain  pulse,  the  carotid,  the  femoral 
and  the  tibial.  The  subject  lay  on  his  back  in  all  tests.  The  first  form  of  brain 
plethysmograph  was  used  for  most  of  the  work,  the  second  form  for  a  part, 
however.  To  obtain  the  carotid  pulse,  a  funnel-shaped  cup  was  covered  with 
rubber  of  medium  thinness,  and  a  square  piece  of  cork  about  four  millimeters 
thick  was  attached  to  the  rubber  by  means  of  beeswax.  The  cup  was  inverted  on 
the  throat,  and  the  cork  placed  over  the  carotid.  Straps  attached  to  the  sides  of 
the  cup  near  its  smaller  end  were  then  fastened  firmly  around  the  neck,  and  a  tube 
was  led  from  the  smaller  end  of  the  cup  to  a  piston  recorder. 

The  femoral  was  recorded  as  follows :  A  strip  of  heavy  card-board  two  inches 
wide  was  bandaged  to  the  outside  of  the  right  leg.  It  extended  up  past  the  hip. 
A  shallow  tambour  cup  covered  with  medium  weight  rubber  and  a  piece  of  cork 
four  millimeters  thick  and  one  centimeter  in  diameter  was  attached  to  the  center 
of  the  rubber  covering.  The  cup  was  inverted  and  the  cork  placed  upon  the 
femoral.  A  broad  bandage  was  passed  around  the  thigh,  over  the  cup  and 
through  a  slit  in  the  upper  end  of  the  cardboard,  and  was  pinned  or  tied  firmly. 
A  tube  led  from  the  cavity  of  the  cup  to  a  piston  recorder.  The  cardboard  was 
of  course  necessary  to  prevent  the  bandage  slipping  down,  and  was  better  than  a 
belt  around  the  waist  since  it  was  not  influenced  by  respiratory  movements. 

For  the  tibial  curve  an  elliptical  rubber  bulb  having  a  moderately  heavy  wall 
was  placed  over  the  artery,  and  a  bandage  passed  firmly  over  it  and  around  the 
ankle.     The  bulb  was  also  connected  to  a  piston  recorder. 

."iO 


THE   HEART   RATE  AND   PULSE   TRANSMISSION    TIME  5^ 

The  recording  points  were  arranged  as  nearly  as  possible  along  a  plumb  line. 
An  arc  was  struck  with  each  to  serve  as  a  line  of  reference.  Similar  arcs  were 
also  struck  at  the  end  of  each  record.  On  the  first  record  of  each  night's  work, 
the  recording  needles  were  set  level  and  the  kymograph  was  run  a  few  centimeters. 
This  gave  the  position  of  the  level  line  of  each  recorder.  The  order  from  the 
top  down  was  the  abdominal  breathing,  the  chest  breathing,  the  indicator  line, 
the  time  line,  the  femoral,  the  brain,  the  carotid  and  the  tibial.  The  time  curve 
was  given  by  an  electric  marker.  This  was  driven  by  a  current  which  was  inter- 
rupted by  a  tuning  fork  at  the  rate  of  fifty  times  per  second.  The  kymograph 
was  run  rapidly  enough  that  the  intervals  desired  could  easily  be  measured  in 
two-hundredths  of  a  second,  and  with  some  accuracy  in  one-thousandths  of  a 
second.  A  long  paper  would  usually  ascend  about  five  millimeters  on  the  kymo- 
graph in  going  around  once.  Such  a  rise  did  not  cause  a  measurable  error,  but 
made  it  possible  to  rotate  twice  without  stopping,  and  yet  not  obscure  the  record. 
This  was  often  necessary  in  order  to  include  a  period  long  enough  for  a  reaction 
to  take  place. 

After  the  apparatus  was  adjusted,  one  or  two  records  were  taken  while  the 
subject  was  still  awake.  He  was  then  allowed  to  go  to  sleep,  and  as  many  records 
as  possible  were  taken  before  he  awakened.  In  a  part  of  these  the  subject  slept 
deeply  and  evenly ;  in  a  part  the  assistant  gave  a  stimulus  which  disturbed  but  did 
not  awaken  the  subject;  and  a  part  were  taken  when  periods  of  restricted  breath- 
ing alternated  with  deeper,  freer  breathing  and  each  record  was  timed  so  as  to 
include  the  change  of  breathing.  After  the  subject  awakened  another  record 
was  taken. 

After  every  record  the  assistant  reported  the  condition  of  the  subject  during 
the  test,  and  after  awakening,  the  subject  was  asked  for  any  introspections. 

The  evaluation  of  the  records  of  these  tests  was  the  most  difficult  task  in  the 
entire  investigation.  In  the  first  place,  the  reports  of  the  assistant  and  the 
subject's  introspections  were  examined,  and  all  records  in  which  the  condition 
of  the  subject  was  doubtful  were  thrown  out.  Also  those  were  thrown  out  in 
which  movement  of  the  subject,  breaking  or  leaking  of  any  of  the  apparatus,  or 
other  accidental  circumstance  had  so  obscured  the  curves  as  to  make  an  accurate 
evaluation  impossible.  However,  a  few  were  retained  in  which  either  the  tibial 
or  femoral  curves  were  too  uncertain  to  be  used.  Those  of  value  were  worked 
up  as  follows. 

At  the  instrument  shops  of  the  University,  three  circles  of  tin  were  cut,  one 
with  a  radius  of  8.7  cm.,  one  with  a  radius  of  10  cm.,  and  one  with  a  radius  of 
12.3  cm.  It  will  be  remembered  that  these  were  the  lengths  of  the  writing  levers 
of  the  dififerent  recorders  used.  A  small  hole  was  drilled  in  the  center  of  each 
circle.  Then  a  sector  of  approximately  thirty  degrees  was  cut  from  each  circle, 
except  that  a  small  ring,  5  mm.  in  diameter,  was  left  around  the  hole  in  the  center. 

The  first  step  with  each  record  was  to  draw  the  level  lines  for  each  curve ;  i.  e., 
the  lines  which  the  recording  needle  would  have  made  if  it  had  remained  stationary 
in  a  level  position.     This  involved  only  the  drawing  of  lines  parallel  to  the 


52  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

indicator  line  and  at  the  required  distance  from  it.  But  it  is  important  to  get 
these  accurate.  A  slight  error  in  the  position  of  the  level  line  is,  of  course,  of 
more  importance  when  the  curve  is  far  from  the  line,  than  it  is  to  not  reduce  to 
level  when  the  curve  is  near  the  line ;  for  the  displacement  is  more  in  proportion 
the  farther  the  needle  departs  from  its  level.  Then  the  beginning  of  each  pulse- 
beat  was  marked  with  a  needle,  and  by  use  of  a  magnifying  glass.  This  was  the 
most  uncertain  part  of  the  process.  It  is  impossible  to  determine  with  finality 
the  beginning  of  a  pulse,  iln  some  tracings  there  is  a  definite  bend  in  the  curve 
where  the  main  rise  begins.  In  such  cases  this  point  was  taken  as  the  beginning. 
In  other  curves,  the  transition  from  one  pulse  to  another  was  rounded  and 
indefinite.  In  such  cases  a  strip  of  celluloid  on  which  parallel  lines  were  ruled  one 
millimeter  apart,  was  placed  so  that  one  of  the  lines  coincided  with  the  level  line 
of  the  recorder,  and  the  lowest  point  of  the  curve  was  observed  and  marked  as 
the  beginning  of  the  pulse.  The  femoral  pulse  was  particularly  troublesome.  In 
some  cases  it  seemed  to  be  complicated  by  a  slight  movement  somewhat  like  that 
of  a  venous  pulse,  of  the  real  nature  of  which  I  am  not  certain.  The  instrument 
with  which  the  pulse  is  taken  certainly  makes  a  difference  in  the  time  at  which 
the  rise  will  show  itself.  The  first  form  of  brain  plethysmograph  is  obviously 
more  analogous  to  the  covered  cup  with  which  the  carotid  is  taken  than  is  the 
second  form  of  brain  plethysmograph.  And  we  shall  find  that  the  results  from 
the  first  form  were  much  the  more  reasonable.  Any  pressure  like  the  tension  of 
the  rubber  of  the  covered  instruments  tends  to  delay  and  round  the  rise.  Obvi- 
ously, so  far  as  the  pulse  is  from  small  arteries,  a  condition  of  constriction  of 
the  vessels  might  interfere  with  the  rise  showing  itself.  In  all  results  then,  errors 
of  unknown  character  are  involved.  If  one's  standard  could  be  kept  the  same 
and  the  shape  of  the  pulse  did  not  change  throughout  a  given  set  of  records,  the 
error  would  at  least  be  reduced  to  a  minimum.  But  such  an  ideal  is  never 
attained,  and  the  irregularities  due  to  uncertainties  as  to  the  beginning  of  the 
pulse  very  nearly  rendered  useless  the  exact  methods  I  was  able  to  employ  in 
other  respects. 

The  beginning  of  each  pulse  was  then  reduced  to  the  level  line  and  the 
corresponding  position  marked  on  the  time  record.  To  do  this,  a  celluloid 
straight-edge  was  laid  along  the  indicator  line  and  held  in  position  by  weights. 
The  sector  whose  radius  is  the  length  of  the  recording  lever  concerned,  was  placed 
so  that  one  of  its  radii  lay  along  the  level  line  and  its  arc  was  in  contact  with  a 
needle  thrust  through  the  beginning  of  the  pulse.  One  side  of  a  square  was 
placed  against  the  straight-edge  and  moved  along  it  until  the  other  side  met  the 
arc  of  the  sector,  which  it  should  do  at  the  intersection  of  the  arc  and  the  level 
line.  This  gave  the  position  desired  on  the  time  line  which  was  marked  with  a 
needle.  Different  lengths  of  marks  were  used  for  the  different  arteries,  so  that 
they  could  be  easily  distinguished.  The  time  was  then  counted  by  use  of  a 
magnifying  glass  from  each  carotid  mark  to  the  next,  for  the  length  of  the 
pulse;  from  the  carotid  to  the  brain,  from  the  carotid  to  the  femoral,  and  from 
the  femoral  to  the  tibial  for  the  transmission  times.  Where  the  femoral  could 
not  be  used,  the  count  was  made  from  the  carotid  to  the  tibial. 


THE   HEART   RATE  AND   PULSE   TRANSMISSION    TIME  53 

In  all  this  process  certain  errors  are  involved  which  must  be  corrected.  In  the 
first  place,  it  is  generally  impossible  to  arrange  the  recording  points  exactly  in  a 
line  perpendicular  to  the  indicator  and  level  lines.  To  measure  the  error  due 
to  this,  the  straight-edge  is  placed  along  the  indicator  line.  One  side  of  the 
square  is  moved  along  it  until  the  other  side  touches  one  of  the  arcs  struck  at 
the  beginning  by  the  needles,  and  a  line  is  drawn  along  this  side.  A  similar  line 
is  drawn  for  each  of  the  arcs  unless  two  or  more  of  them  fall  on  the  same  one. 
A  check  upon  accuracy  is  that  the  vertical  Hne  should  be  tangent  to  the  arc  at  the 
intersection  of  the  level  line.  The  distances  between  the  vertical  line  of  the 
carotid,  and  those  of  the  brain  and  femoral,  and  the  distance  between  the  line  of 
the  femoral  and  that  of  the  tibial  are  measured.  Where  the  femoral  is  not  used, 
the  measurement  is  from  the  carotid  to  the  tibial.  These  measurements  give  the 
corrections  to  be  added  to  or  subtracted  from  the  positions  of  the  pulse-beats. 
If  the  carotid  vertical  is  in  front  of  the  brain  or  femoral,  the  correction  is  to  be 
added  to  the  latter,  if  the  carotid  is  behind,  the  correction  is  subtracted.  Likewise 
if  the  femoral  is  in  front  of  the  tibial,  their  difference  is  added;  if  the  femoral 
is  behind,  the  difference  is  subtracted.  In  practice,  the  differences  were  converted 
into  terms  of  time  by  reference  to  the  time  record,  and  the  results  added  to  or 
subtracted  from  the  transmission  times.  Where  the  kymograph  ran  regularly, 
only  one  evaluation  of  the  differences  in  terms  of  time  was  required;  but  when 
the  rate  was  irregular,  of  course  several  were  necessary. 

Furthermore,  it  was  impossible  to  have  all  recorders  in  exactly  the  same  plane, 
and,  consequently,  all  needles  did  not  move  quite  parallel  with  the  plane  of  the 
paper.  On  this  account,  any  great  rise  or  fall  in  the  curve  caused  an  extra 
displacement  of  the  writing-point  forward  or  backward.  The  arc  struck  at  the 
beginning  is  not  a  perfect  circle;,  it  was  somewhat  elliptical.  To  obtain  the 
correction  necessary  at  any  given  elevation  of  the  curve,  a  pin  is  thrust  through 
the  arc  at  the  beginning,  at  the  given  elevation,  the  corresponding  sector  is  placed 
with  one  radius  along  the  level  line,  and  its  own  arc  in  contact  with  the  pin. 
The  length  of  level  line  intersected  between  the  arc  of  the  sector  and  the  arc  struck 
by  the  needle  is  the  correction,  the  amount  we  must  imagine  the  pulse  to  be  moved 
backward.     When  of  appreciable  amount,  this  correction  was  always  carried  out. 

Lastly,  if  on  account  of  unevenness  of  the  paper,  a  needle  presses  too  hard 
at  any  place,  this  extra  pressure  will  slightly  straighten  the  curve  near  the  end 
of  the  needle,  and  displace  the  writing  point  backward.  If  the  heaviness  of  the 
line  shows  such  an  error  to  be  active  to  a  great  degree,  allowance  must  be  made 
or  the  record  thrown  out.  An  indication  of  the  correction  may  of  course  be 
obtained  if  the  place  is  near  the  arcs  struck  at  the  beginning  or  the  end. 

After  the  record  had  been  counted  and  the  corrections  made,  the  results  were 
charted  as  follows.  Coordinate  paper  was  used  on  which  the  lines  were  ruled 
approximately  six  millimeters  apart.  For  most  of  the  records,  four  heavy  hori- 
zontal lines  were  drawn  to  serve  as  standard  lines.  To  plot  the  heart-rate,  the 
standard  line  for  the  heart-rate  was  given  the  value  of  thirty-five,  forty,  fifty, 
fifty-five  or  sixty  fiftieths  of  a  second  (represented  as  35  P,  40  P,  50  P,  55  P,  or 


54  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

60  P  at  the  left  end  of  the  line),  and  each  unit  of  space  above  or  below  was  given 
the  value  of  one  fiftieth  of  a  second.  Above  is  positive,  below  negative  to  the 
standard.  Units  of  distance  along  it  represent  pulse-beats.  Points  were  placed 
in  the  appropriate  positions  on  the  vertical  lines  to  mark  the  length  of  each  pulse. 
Thus  if  the  standard  is  50  P,  a  pulse  of  forty-eight  fiftieths  of  a  second  in  length 
will  lie  two  spaces  below  the  standard,  one  of  fifty-three  fiftieths  of  a  second  in 
length  will  lie  three  spaces  above.  A  curve  was  then  drawn  through  these  points. 
A  rise  in  the  curve,  therefore,  means  a  slower  heart-rate ;  a  fall  in  the  curve  means 
a  faster  heart-rate. 

To  plot  the  transmission  times,  the  method  was  similar.  Times  from  the 
carotid  to  the  femoral  and  from  the  femoral  to  the  tibial  were  expressed  in  fiftieths 
of  a  second.  These  two  were  also  added  together,  giving  the  time  from  the 
carotid  to  the  tibial,  which  was  also  expressed  in  fiftieths  of  a  second.  It  was 
plotted  separately,  since,  being  a  longer  time,  it  is  less  obscured  by  errors  of 
marking  and  counting.  The  time  from  the  carotid  to  the  brain  was  expressed  in 
two-hundredths  of  a  second.  The  standard  line  for  the  carotid-femoral  time  was 
given  the  value  of  three,  four  or  five  fiftieths  of  a  second  (represented  as  3  C.  F., 
4  C.  F.,  or  5  C.  F.,  at  the  left  of  the  line),  and  each  unit  of  space  above  or  below 
was  given  the  value  of  one-hundredth  of  a  second.  The  standard  line  for  the 
femoral-tibial  time  was  given  the  value  of  three,  four  or  five  fiftieths  of  a 
second,  and  that  for  the  carotid-tibial  time  was  given  the  value  of  six,  seven, 
eight  or  nine  fiftieths  of  a  second  (represented  as  3  F.  T.,  4  F.  T.,  or  5  F.  T.,  and 
6  C.  T.,  7  C.  T.,  8  C.  T.,  or  9  C.  T.,  respectively).  Spaces  above  and  below 
had  the  value  of  one-hundredth  of  a  second.  The  standard  line  for  the  carotid- 
brain  time  was  given  the  value  of  zero,  two,  three  or  four  two-hundredths  of  a 
second  (represented  as  o  C.  B.,  2  C.  B.,  3  C.  B.,  or  4  C.  B.),  and  each  space 
above  or  below  had  the  value  of  one  four-hundredth  of  a  second.  The  vertical 
line  on  which  was  represented  the  transmission  times  of  a  certain  pulse  wave,  was 
also  the  line  on  which  was  represented  the  length  of  the  preceding  pulse  wave. 

To  chart  the  brain  volume,  the  distance  of  the  beginning  of  each  pulse  beat 
from  the  level  line  of  the  recorder  was  measured,  and  marked  as  positive  or 
negative.  Then  the  same  distances  were  laid  off  on  the  corresponding  vertical 
lines  of  the  coordinate  paper,  using  the  standard  line  in  the  place  of  the  level  line 
on  the  original  record.  A  curve  drawn  through  the  points  thus  marked  repre- 
sents the  volume  changes  in  terms  of  the  lowest  points  of  the  pulse-beats. 

The  chest  breathing  only  was  plotted.  The  level  line  of  the  tambour  was 
drawn.  The  distance  of  the  breathing  curve  above  and  below  this  line  was 
measured  in  millimeters  at  a  position  corresponding  to  the  beginning  of  each 
pulse,  and  at  the  crest  and  trough  of  each  breath.  The  standard  line  on  the 
coordinate  paper  was  given  the  value  zero,  and  each  space  above  or  below  it  the 
value  of  one  millimeter.  The  measurerhents  were  then  counted  off  on  the  cor- 
responding vertical  lines,  and  the  points  obtained  connected  with  a  curve.  Thus 
the  depth  of  inspiration  is  plotted  below  the  standard  line,  the  height  of  expiration 
above  it. 


THE   HEART   RATE  AND   PULSE   TRANSMISSION   TIME  55 

Since  the  records  were  several  minutes  apart,  and  the  brain  tracing  might  be 
changed  artificially  between  records,  the  position  of  the  brain  curve  on  one  chart 
cannot  be  compared  with  that  on  another. 

'In  most  of  the  charts,  the  top  standard  line  is  used  for  the  brain  volume. 
The  next  is  used  for  the  carotid-tibial  time,  which  is  represented  by  a  smooth 
line,  and  for  the  breathing,  which  is  represented  by  a  dotted  line.  On  the  third 
standard  from  the  top  are  plotted  the  carotid-brain  time,  represented  by  a  smooth 
line,  and  the  femoral-tibial  time,  represented  by  a  dotted  line.  The  bottom  line 
is  standard  for  the  heart-rate,  drawn  as  a  smooth  curve,  and  the  carotid-femoral 
time,  drawn  as  a  dotted  curve.  Where  a  different  system  was  used,  the  arrange- 
ment will  be  explained  in  describing  the  individual  record. 

Lastly,  it  should  be  stated  that  all  the  records  were  first  marked  and  counted 
and  the  necessary  corrections  calculated  before  any  were  charted.  Each  record 
was  marked  without  reference  to  whether  it  was  from  waking  or  sleeping,  a 
stimulus  or  even  sleep,  and  without  noting  how  the  results  were  coming  out.  It 
was  only  after  the  charting  was  well  advanced  that  I  began  to  see  what  the  con- 
clusions would  be.  In  this  way  I  attempted  to  escape  the  influence  of  any 
previous  theory  or  suggestion. 

The  second  subject  served  for  the  main  part  of  this  work.  One  night's  results 
were  obtained  from  the  first  subject  just  before  he  left  the  city;  but  they  included 
only  the  brain,  carotid  and  femoral,  and  were  not  very  satisfactory.  The  appa- 
ratus for  the  elimination  of  movement  was  not  used.  A  few  records  for  special 
purposes  were  taken  from  another  subject  Bi.,  using  the  carotid  and  radial. 

Typical  Results 

I  turn  now  to  a  description  of  several  typical  charts.  The  sides  of  the  charts 
were  multiplied  by  one- fourth  in  the  reproduction. 

H.,  May  20,  VI  (Fig.  57,  Plate  51). — The  subject  was  asleep.  Periods  of 
slightly  restricted  breathing  were  alternating  with  periods  of  somewhat  freer 
breathing ;  neither  period  was  extreme.  This  record,  especially  in  the  latter  part, 
was  a  period  of  restriction.  The  chart  shows  the  decreasing  amplitude  of  breath- 
ing and  the  check  in  inspiration.  The  brain  volume  rose  a  little.  The  carotid- 
femoral  curve  shows  no  very  certain  change  of  level,  but  possibly  a  rise.  The 
other  transmission  times  are  obviously  increased.  There  is  a  very  large  respiratory 
wave  in  the  heart-rate,  and  the  average  heart-rate  was  slowed  somewhat  during 
the  record.  The  rate  increases  with  inspiration  and  decreases  with  expiration, 
except  that  the  change  is  somewhat  delayed.  The  respiratory  wave  in  the  trans- 
mission time  is  of  course  most  reliable  in  the  carotid-tibial.  The  crest  of  the 
transmission  time  wave  is  usually  on  the  rise  or  crest  of  the  wave  in  the  volume 
of  the  brain.  The  trough  of  the  transmission  wave  tends  to  be  somewhere  on  the 
fall  from  crest  to  trough  of  volume.  The  wave  in  the  brain  volume  rises  with 
inspiration  and  falls  with  expiration,  except  that  the  volume  changes  are  delayed, 
especially  the  fall. 

H.,  May  25,  II  (Fig.  58,  Plate  51). — The  subject  was  awake  but  drowsy. 


56  STUDIES  IN  THE  CIRCULATION  AND  SLEEP 

The  breathing  was  irregular,  the  third  and  the  fifth  breath  much  restricted.  The 
first  four  brain  pulses  were  obscured,  their  exact  position  doubtful.  This  portion 
is  marked  by  a  dotted  line.  The  brain  volume  was  low  at  first,  rose  in  the  center 
and  fell  again  at  the  end.  The  transmission  time  was  first  rapid,  then  slowed, 
then  accelerated  again,  and  finally  slowed  a  little  toward  the  end.  The  slowing 
of  transmission  rate  corresponds  to  a  rise  of  brain  volume,  the  acceleration  to  a 
fall  of  brain  volume;  but  the  change  in  volume  is  delayed  a  little  behind  the 
change  in  transmission  time.  The  heart-rate  curve  fell  with  the  rise  in  brain 
volume  and  transmission  curves,  and  rose  with  the  decrease  of  volume  and  more 
rapid  transmission.  It  was  apparently  falling  again  with  the  slowing  trans- 
mission.    It  shows  a  respiratory  wave,  but  a  comparatively  small  one. 

H.,  May  25,  VI  (Fig.  59,  Plate  51). — The  subject  was  asleep.  The  breathing 
was  restricted  in  the  first  part  and  became  freer  in  the  last  part  of  the  record. 
The  brain  volume  was  rising  slightly  at  first,  and  fell  toward  the  end  with  the 
freer  breathing.  The  femoral  was  uncertain  and  only  the  carotid-tibial  and 
carotid-brain  times  were  measured.  The  transmission  became  more  rapid 
towards  the  end  with  the  fall  of  volume,  the  change  in  transmission  beginning 
before  the  change  in  volume.  The  respiratory  wave  in  transmission  (carotid- 
tibial  especially)  is  irregular  and  uncertain;  but  apparently  the  crest  of  the  trans- 
mission curve  comes  on  the  trough  or  rise  of  the  volume  wave;  the  trough  of 
transmission  is  somewhere  on  the  fall  of  volume.  The  heart-rate  shows  a  medium 
breathing  wave.  The  rate  became  more  rapid  during  the  first  period  of  rising 
volume,  and  slower  at  the  end  when  the  volume  was  low.  And  yet  one  cannot 
infer  that  the  heart-rate  change  caused  the  volume  change;  firstly,  because  the 
rate  was  not  much  slower  at  the  end  than  at  the  first  of  the  record,  although 
the  volume  was  greatly  decreased;  secondly,  because  the  pressure,  indicated  by 
the  rapid  transmission  time,  was  higher  at  the  period  of  low  volume. 

H.,  May  2^,  XI  (Fig.  60,  Plate  51). — The  subject  was  awake  but  drowsy. 
This  was  a  period  of  drowsing  with  slight  restriction  of  breathing.  There  was 
some  rise  of  brain  volume.  The  femoral  was  obscure ;  only  the  carotid-tibial  and 
carotid-brain  were  measured.  The  transmission  curves  rose,  indicating  fall  of 
pressure.  The  respiratory  waves  in  the  transmission  are  irregular.  The  heart- 
rate  shows  a  respiratory  wave  smaller  than  that  in  VI.  The  curve  fell  (faster 
heart-rate)  while  the  volume  and  transmission  curves  rose. 

H.,  June  8,  III  (Fig.  61,  Plate  51). — The  subject  was  asleep.  At  the  cross 
the  assistant  touched  him,  he  stopped  snoring  and  breathed  more  freely.  He 
began  to  breathe  heavily  again  just  after  this  record  closed.  The  pulse-respira- 
tion ratio  during  the  first  part  of  the  record  was  4.25 ;  that  in  the  latter  part  was 
4.6.  One  or  two  pulse-beats  were  obscured  by  a  movement  of  the  head,  and 
omitted.  A  few  others  were  omitted  in  some  of  the  curves  because  exceptionally 
uncertain.  The  brain  volume  fell  markedly  following  the  stimulus.  The  brain 
was  recorded  by  means  of  the  second  form  of  brain  plethysmograph.  As  noted 
above  in  the  description  of  method,  this  is  not  analogous  to  the  covered  cup  used 
to  i-ecord  the  carotid,  and  allows  the  rise  of  the  pulse  to  show  itself  more  quickly 


THE  HEART   RATE  AND   PULSE   TRANSMISSION   TIME  57 

than  with  the  other  instrument.  The  present  curve  illustrates  the  point.  The 
standard  line  for  the  carotid-brain  time  has  the  value  of  zero,  and  the  curve  is 
sometimes  even  negative,  an  obvious  impossibility. 

With  the  first  form  of  brain  plethysmograph  which  was  used  in  the  preceding 
records,  the  times  ranged  around  three  or  four  two-hundredths  of  a  second,  a 
much  more  probable  value.  And  yet,  if  each  instrument  is  compared  only  with 
itself,  the  direction  of  change  of  the  curve  seems  to  be  practically  the  same  with 
both  instruments.  In  this  particular  record  I  found  it  especially  difficult  and 
uncertain  to  mark  the  brain  pulses. 

The  transmission  time  curves  showed  a  tendency  to  rise  during  the  first  part 
of  the  record,  and  then  fell  after  the  stimulus.  This  fall  lasted  until  the  brain 
curve  was  well  down  its  descent.  The  transmission  curves  then  rose  in  the  latter 
part  while  the  brain  continued  to  decrease.  The  heart-rate  curve  rose  (slower 
rate)  after  the  stimulus,  and  seems  to  have  been  responsible  for  the  fall  of 
pressure  indicated  by  the  slowing  transmission  time  near  the  end.  There  is  a 
considerable  respiratory  wave  in  the  heart-rate;  but  the  respiratory  wave  in  the 
transmission  time  is  uncertain  and  irregular  in  its  relations. 

H.,  June  8,  IV  (Fig.  62,  Plate  52). — The  subject  was  asleep.  The  assistant 
touched  him  at  the  cross,  he  stopped  snoring  and  breathed  more  freely.  The 
pulse-respiration  ratio  during  the  first  part  of  the  record  was  4.25  ;  that  during  the 
last  part  was  4.2.  The  femoral  was  too  obscured  to  be  used  and  only  the  carotid- 
tibial  and  carotid-brain  were  counted.  The  same  remarks  apply  to  the  brain 
curve  as  in  the  preceding  chart.  The  brain  volume  was  rising  a  little  before  the 
stimulus,  and  fell  fairly  rapidly  after  the  stimulus.  The  heart-rate  increased 
before  the  stimulus,  decreased  afterward,  and  showed  a  slight  tendency  to  increase 
again  near  the  end.  The  carotid-tibial  curve  rose  before  the  stimulus,  fell  and 
remained  low  until  the  brain  had  nearly  completed  its  descent,  then  rose  again  at 
the  end.  The  carotid-brain  curve  is  not  so  reliable.  It  fell  slightly,  then  began 
to  rise  when  the  stimulus  came.  Several  pulses  after  the  stimulus  it  fell  markedly, 
and  was  just  beginning  to  rise  again  at  the  end.  The  breathing  wave  in  the 
heart-rate  was  large,  that  in  the  transmission  times  was  irregular. 

H.,  June  34,  I  (Fig.  63,  Plate  52). — The  subject  was  awake.  The  record  is 
too  short  to  be  certain  of  the  significance  of  changes.  Apparently  the  brain 
volume  shows  a  trough  and  the  transmission  times  indicate  a  trough  delayed  com- 
pared with  the  volume.  But  the  carotid-brain  curve  does  not  agree  with  this. 
The  carotid-tibial  time  averages  about  8.5  fiftieths  of  a  second.  The  respiratory 
wave  in  the  heart-rate  is  moderate.  In  this  and  all  the  following  charts  the 
first  form  of  brain  plethysmograph  was  used. 

H.,  June  24.,  IV  (Fig.  64,  Plate  52). — The  subject  was  asleep.  The  assistant 
touched  him  at  the  cross  and  disturbed  him.  The  pulse-respiration  ratio  before 
the  disturbance  was  3.7,  that  after  the  disturbance  was  3.25.  The  brain  volume 
fell  during  the  disturbance.  The  transmission  time  curves  fell  at  the  same  time, 
the  most  consistent  reaction  being  in  the  carotid-tibial.  The  heart-rate  shows  a 
large  breathing  wave  and  was  slowed  as  a  result  of  the  stimulus.     The  crest  of 


58  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

the  respiratory  wave  in  the  carotid-tibial,  so  far  as  it  can  be  judged,  falls  some- 
where on  the  rise  of  the  wave  in  the  brain  volume.  The  other  curves  are 
irregular. 

H.,  June  24,  VII  (Fig.  65,  Plate  52). — The  subject  was  asleep.  A  stimulus 
was  given  at  the  cross  and  resulted  in  a  period  of  freer  breathing.  The  pulse- 
respiration  ratio  before  the  stimulus  was  3.5,  that  after  the  stimulus  was  3.25. 
The  stimulus  caused  a  fall  of  brain  volume.  The  heart  rate  at  first  showed  a  large 
respiratory  wave.  The  effect  of  the  stimulus  was  to  give  an  average  increase  in 
heart-rate  for  a  few  pulse-beats,  and  then  an  extreme  slowing  with  much  reduced 
respiratory  wave.  The  transmission  time  curves  fell  after  the  stimulus.  This 
fall  was  partly  recovered  from  before  the  end,  probably  as  a  result  of  the  slower 
heart-beat,  but  the  net  result  was  a  more  rapid  transmission  with  decreased  brain 
volume.  The  crest  of  the  breathing  wave  in  the  transmission  time  curves  comes 
for  the  most  part  on  the  trough  of  volume.  There  is  a  low  brain  volume  at  the 
beginning  without  any  apparent  reason  (perhaps  the  end  of  a  preceding  fall  with 
break  in  breathing). 

H.,  June  24,  IX  (Fig.  66,  Plate  53). — The  subject  was  asleep  and  a  stimulus 
was  given  at  the  crosses.  He  moved  and  was  considerably  disturbed.  The 
breathing  became  freer.  The  pulse-respiration  ratio  at  the  beginning  was  3.5 ;  at 
the  end  it  was  3.  The  brain  volume  decreased  markedly.  The  heart-rate  was 
increasing  before  the  stimulus.  The  effect  of  the  stimulus  was  an  extreme  slow- 
ing. In  the  first  part  of  the  record  the  transmission  time  curves  were  falling 
along  with  the  increasing  heart-rate  and  slowly  rising  brain  volume.  The  first 
effect  of  the  stimulus  was  a  still  more  rapid  transmission  time  (higher  pressure), 
but  towards  the  end  this  was  counteracted,  apparently  by  the  decreasing  heart- 
rate.  So  far  as  it  can  be  determined,  the  crest  of  the  breathing  wave  in  the 
transmission  time  corresponds  to  the  trough  of  volume. 

/.,  November  21,  XIII  (Fig.  67,  Plate  53). — This  is  a  chart  of  one  of  the 
records  taken  from  the  first  subject.  The  smooth  curve  on  the  top  standard 
line  is  the  carotid-femoral  time;  the  dotted  curve  is  the  breathing.  The  second 
standard  line  is  that  of  the  heart-rate.  The  bottom  line  is  for  the  carotid-brain 
time. 

The  subject  was  asleep  at  the  start.  At  the  cross  the  assistant  started  to 
awaken  him,  and  he  was  awake  by  the  end  of  the  record.  In  awakening,  he 
moved,  and  the  brain  recorder  was  thrown  entirely  off  the  paper  so  that  it  had 
to  be  regulated  artificially.  This  so  obscured  the  volume  change  that  I  have  not 
attempted  to  plot  it.  The  breathing  was  irregularly  disturbed,  and  finally  became 
much  shallower.  The  pulse-respiration  ratio  was  4.4  during  sleep,  and  3.7  in  the 
latter  part  of  the  record  during  awakening.  In  the  earlier  part  of  the  record, 
the  heart-rate  showed  a  large  breathing  wave  and  a  prominent  Traube-Hering 
wave.  There  is  a  suggestion  that  the  increase  in  heart-rate  in  the  Traube-Hering 
wave  goes  with  the  higher  position  of  the  transmission  time  curve  (passive  phase), 
the  decrease  in  rate  (rise  of  curve)  goes  with  the  lower  position  of  the  trans- 


THE   HEART   RATE  AND   PULSE   TRANSMISSION    TIME  59 

mission  curve  (active  phase).  With  awakening,  both  respiratory  and  Traube- 
Hering  waves  were  very  much  decreased  in  the  heart-rate.  The  effect  of  awaken- 
ing on  the  transmission  curves  was  a  definite  fall  (rise  of  blood  pressure). 

Bi.,  March  22,  II  (Fig.  68,  Plate  53). — This  is  one  of  several  records  taken 
from  the  subject  Bi.  to  test  the  effects  of  strong  stimuli  and  of  deep  breathing 
upon  the  transmission  time.  The  pulse  tracings  taken  were  the  hand  (by  means 
of  the  rubber  bulb)  and  the  carotid.  The  hand  volume  is  recorded  along  the  top 
standard  line.  The  smooth  curve  on  the  bottom  standard  line  is  the  heart-rate, 
the  dotted  curve  is  the  carotid-hand  time.  A  loud  whistle  was  blown  between  the 
crosses.  It  caused  the  subject  to  jump  and  frightened  him.  I  have  shown  in  a 
previous  work^  that  very  strong  stimuli  may  have  both  an  exciting  and  inhibiting 
effect  upon  the  heart.  The  reaction  is  rarely  so  extreme  as  this,  and  it  is  im- 
possible to  say  whether  this  case  is  due  entirely  to  the  strong  stimulus  or  in  part 
to  the  relief  the  subject  felt  after  the  whistle  (which  he  knew  would  come).  But 
I  am  reproducing  this  chart  because  such  reactions  in  a  smaller  degree  do  often 
take  place  with  strong  stimuli  when  the  subject  does  not  expect  the  stimulus, 
is  not  under  strain  and  does  not  feel  relief  afterward;  also  because  it  shows 
the  effect  of  such  heart-rate  changes  upon  the  transmission  time.  It  will  be  seen 
that  the  heart-rate  was  increasing  when  the  stimulus  came,  and  decreased  markedly 
afterward.  The  hand  volume  fell  after  the  stimulus,  then  returned  to  normal. 
The  transmission  curve  shows  a  sustained  rise  (lower  pressure)  soon  after  the 
stimulus,  perhaps  an  effect  of  the  decreased  heart-rate.  There  is  a  noticeable 
Traube-Hering  wave  in  the  hand  volume,  somewhat  obscured  by  the  reaction,  and 
a  marked  one  in  the  heart-rate,  especially  in  the  first  part  of  the  record.  There 
is  also  a  suggestion  of  such  a  wave  in  the  transmission  curve.  The  trough  of 
volume,  on  the  whole,  seems  to  correspond  to  the  slower  transmission  (lower 
pressure)  and  the  crest  of  volume  to  the  faster  transmission.  Also  the  heart- 
rate  seems  to  increase  with  the  fall  of  volume  and  slower  transmission  and  to 
decrease  with  the  rise  of  volume  as  a  rule.  But  these  relations  are  not  exact, 
perhaps  on  account  of  delayed  effect. 

Bi.,  April  2,  I  (Fig.  69,  Plate  53).— This  is  another  record  from  the  same 
subject  as  the  last  one.  The  smooth  curve  is  the  heart-rate.  The  dotted  curve 
is  the  carotid-hand  time.  The  subject  was  breathing  very  long  and  deeply.  The 
letters  at  the  top  indicate  the  positions  of  the  crests  and  troughs  of  the  respiratory 
waves  in  the  hand  volume.  The  waves  in  the  transmission  curve  are  in  the 
same  direction  as  those  in  the  heart-rate,  except  slightly  delayed.  The  crest  of 
volume  occurs  at  or  just  after  the  lowest  point  in  the  transmission  wave  (highest 
pressure),  the  trough  of  volume  occurs  at  or  just  after  the  highest  point  in  the 
transmission  wave  (lowest  pressure).  A  part  of  the  object  in  reproducing  this 
chart  is  to  show  to  what  extent  the  method  gives  consistent  and  accurate  results. 
Taken  within  a  single  record  in  this  way,  it  seems  reasonably  satisfactory. 

^  "  Organic  Changes  and  Feeling,"  American  Journal  of  Psychology,  1906,  p.  553. 


6o  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

Summary 

In  general,  when  we  consider  merely  the  curves  within  a  single  record,  the 
results  are  fairly  consistent.  A  stimulus  during  sleep  always  causes  a  fall  of 
brain  volume  and  a  faster  transmission  time  (higher  pressure)  ;  and  almost  always 
gives  a  slowed  heart-rate,  which  may  or  may  not  be  preceded  by  a  brief  accelera- 
tion, and  which  may  later  overcome  the  tendencies  making  for  higher  pressure. 
The  pulse-respiration  ratio  may  change  either  way  with  the  slowed  pulse.  This 
slowed  rate  is  certainly  temporary,  since  it  does  not  last  until  after  awakening; 
but  none  of  my  records  was  long  enough  to  measure  its  period.  It  is  probably 
analogous  to  the  fact  that  in  waking  condition  a  strong  stimulus  has  both  an 
exciting  and  inhibiting  effect  upon  the  heart,  and  often  the  inhibition  is  the  more 
prominent.  But  in  sleep,  any  stimulus  that  will  particularly  disturb  the  subject 
usually  shows  both  effects,  particularly  the  inhibitory.  Awakening  gave  faster 
transmission  (higher  pressure)  with  the  first  subject.  The  results  with  stimuli 
are,  then,  consistent  with  the  facts  brought  out  in  the  blood-pressure  tests. 
Whether  the  slowed  heart-rate  played  any  part  there,  with  the  other  previous 
stimulus  which  the  very  test  constitutes,  I  cannot  say.  Perhaps  it  helped  in  some 
of  the  more  rapid  recoveries  of  the  blood-pressure  curve  after  disturbances. 

Only  a  few  cases  analogous  to  the  Traube-Hering  wave,  or  a  part  of  it,  were 
included  in  the  records.  Seven  out  of  the  eight  cases  seemed  to  agree  with  the 
conclusion  in  the  blood-pressure  tests  with  the  subject  H.,  that  higher  pressure 
(faster  transmission)  goes  with  falling  volume,  and  lowering  of  pressure  (slower 
transmission)  goes  with  rising  volume.  With  subject  Bi.,  the  indication  was  that 
the  opposite  relation  holds.  There  is  also  some  suggestion  in  nearly  all  records 
with  all  subjects,  that  the  Traube-Hering  increase  in  the  heart- rate  accompanies 
the  passive  phase  (lower  pressure),  and  the  Traube-Hering  decrease  in  heart-rate 
accompanies  the  active  phase  (higher  pressure).  This  would  be  consistent  with 
the  result  I  obtained  in  the  earlier  work  on  Organic  Changes  if  the  waves  in  the 
hand  there  used  were  passive,  which  seems  to  be  the  more  usual  condition.  But 
more  work  is  necessary  to  be  certain  of  the  true  relation.  The  breathing  wave 
in  the  transmission  time  curves  is  often  mixed  up.  Examination  of  all  the  charts 
shows  that,  as  nearly  as  one  can  judge,  the  crest  of  the  transmission  wave  occurs 
often  on  the  trough,  rise,  or  crest  of  volume,  seldom  on  the  fall ;  the  trough  of 
transmission  curves  occurs  often  on  the  crest  (oftenest),  fall  or  trough  of  volume, 
seldom  on  the  rise.  This  is  fairly  consistent  with  the  blood-pressure  tests.  But 
I  think  the  indicated  low  pressure  is  more  often  at  the  trough  of  volume,  the  high 
pressure  at  the  crest  of  volume  in  the  present  case  than  it  was  in  the  blood- 
pressure  measurements.  Possibly  such  is  the  case  when  the  subject  is  more 
deeply  asleep,  as  in  the  present  case  where  the  test  does  not  constitute  a  stimulus. 
In  the  heart-rate  curve,  the  respiratory  wave  is  very  much  more  prominent  during 
sleep  than  during  waking. 

■  To  compare  the  results  as  to  heart-rate  in  waking  and  sleeping,  I  noted  the 
general  level  of  the  heart-rate  curve  in  each  record  belonging  to  a  given  night's 
work;  then  averaged  those  taken  during  sleep  and  those  taken  during  waking 


THE   HEART   RATE   AND   PULSE   TRANSMISSION    TIME  61 

separately.  The  results  are  expressed  as  the  length  of  a  pulse  in  fiftieths  of  a 
second.  With  the  first  subject,  the  average  of  three  charts  of  waking  was  43; 
the  average  of  seven  charts  of  sleep  was  44.5  (fiftieths  of  a  second).  With  the 
second  subject,  the  averages  were  as  follows.  May  20:  three  waking  gave  56; 
three  sleep  gave  55.  May  25:  four  waking  gave  52;  seven  sleep  gave  52.  June 
8:  two  waking  gave  50.5;  six  sleep  gave  49.3.  June  24:  two  waking  gave  49.5; 
six  sleep  gave  57.7.  There  was,  therefore,  no  significant  change  except  in  one 
case  where  sleep  gave  a  slower  pulse.  The  most  obvious  change  in  the  heart-rate 
is  the  large  respiratory  wave  in  sleep. 

When  we  attempt  to  study  the  transmission  times  during  sleep  and  waking,  the 
results  are  less  satisfactory.  The  records  seem  at  first  sight  quite  contradictory. 
It  is  not  that  the  transmission  time  sometimes  seems  to  increase  and  sometimes 
seems  to  decrease  during  sleep.  But  one  curve  may  show  one  effect  and  others 
the  exact  opposite.  The  carotid-brain,  the  carotid- femoral,  and  the  carotid-tibial 
may  agree  or  disagree  with  each  other.  The  fact  seems  to  be  that  I  was  able  to 
keep  fairly  successfully  to  a  constant  standard  by  which  I  judged  the  beginning 
of  the  pulse-beat  in  a  particular  curve  of  a  given  record.  But  I  was  unable  to 
carry  over  the  same  standard  from  time  to  time  and  apply  it  to  all  records. 
Consequently  with  a  given  record,  the  results  are  regular;  but  a  comparison  of 
records  brings  out  inconsistencies.  Under  these  circumstances,  only  an  average 
can  have  any  real  value.  Obviously,  the  carotid-tibial  times,  since  they  are  the 
longest,  must  be  relatively  least  obscured  by  errors  of  method;  and  they  are,  in 
fact,  least  inconsistent.  Averaging  these  times  for  sleeping  and  waking  (the 
results  being  expressed  in  fiftieths  of  a  second),  we  find  that  the  records  of  May 
20  give  waking  8.37,  sleep  8.66 ;  those  of  May  25  give  waking  8,  sleep  8.8 ;  those  of 
June  8  give  waking  7.5  (only  one  record  usable),  sleep  7.5  (on  the  basis  of  6 
records) ;  those  of  June  24  give  waking  8.37,  sleep  8.9.  Averaging  the  carotid- 
femoral  times  for  the  first  subject  gives  waking  4.7,  sleep  4.9.  Averages  of  the 
other  times  with  both  subjects  lead  to  similar  results.  Furthermore,  the  longest 
time  during  sleep  is  always  longer  than  the  longest  during  waking  condition ;  and 
the  shortest  time  during  waking  is  generally  shorter  than  any  time  during  sleep. 
We  may  conclude  then,  that  the  transmission  of  the  pulse  wave  is  slower  during 
sleep,  and  consequently  the  blood-pressure  lower,  when  the  subject  is  sleeping 
easily  and  the  test  is  by  a  method  that  does  not  constitute  a  stimulus.  This 
agrees  with  the  results  obtained  by  the  methods  used  in  the  blood-pressure  tests 
proper. 


CHAPTER  V 
THE  JUGULAR  PULSE 

The  greater  part  of  this  investigation  has  been  concerned  with  reactions  in  the 
arterial  system.  The  object  of  the  present  section  is  to  study  to  some  extent  the 
changes  in  the  venous  system  which  accompany  sleep.  Particularly,  are  there  any 
appreciable  alterations  of  pressure  in  the  internal  jugulars  which  could  influence 
the  curve  from  the  brain?  The  second  subject  served  for  this  work.  The  receiv- 
ing cup  used  for  the  carotid  pulse,  but  with  the  rubber  dam  under  lower  tension, 
was  placed  over  the  jugular  and  connected  to  the  large  piston  recorder.  The 
brain  volume  was  recorded  along  with  the  venous  pulse  by  use  of  either  the  first 
or  second  form  of  brain  plethysmograph.  The  chest  and  abdominal  breathing 
curves  were  taken  as  usual.  It  would  seem  that  any  congestion  in  the  jugulars 
sufficient  to  cause  a  rise  of  brain  volume  would  likewise  raise  the  jugular  curve. 
Especially,  a  venous  pressure  that  can  overcome  the  relatively  high  tension  of  the 
rubber  in  the  first  form  of  brain  plethysmograph  must  of  necessity  distend  the 
jugular  and  show  itself  by  a  rise  in  the  tracing. 
I  will  describe  extracts  from  four  records. 

H.,  July  20,  V  (Fig.  70,  Plate  54). — ^The  curves,  beginning  at  the  top,  are  the 
abdominal  breathing,  the  chest  breathing,  the  indicator  line,  the  jugular  and  the 
brain  volume.  The  first  form  of  brain  plethysmograph  was  used.  The  first  part 
of  the  extract  is  the  end  of  a  portion  in  which  the  drum  was  run  rapidly.  The 
definite  venous  pulse  is  obvious.  The  jugular  apparatus  had  been  put  on  only 
about  five  minutes  before,  and  the  air  in  the  cup  and  tubes  was  probably  still 
warming  up.  Hence  the  gradual  rise  in  the  curve.  There  is  a  prominent  breath- 
ing wave  in  the  jugular  curve,  which  is  undoubtedly  in  part  due  to  movement  in 
the  chest  wall  and  neighboring  tissue  of  the  throat.  In  fact,  it  is  practically 
impossible  to  eliminate  this  error. 

The  subject  was  already  partly  asleep  when  the  extract  began.  At  a,  b,  c,  d, 
and  e,  there  are  periods  of  increased  breathing  with  accompanying  fall  of  brain 
volume  of  greater  or  less  extent.  The  brain  curve  was  much  more  nearly  the 
waking  condition  at  the  end  than  at  the  beginning.  There  were  no  corresponding 
definite  changes  in  the  jugular. 

H.,  July  20,  VIII  (Fig.  71,  Plate  55). — The  jugular  cup  had  been  carefully 
readjusted  and  the  strap  slightly  tightened  to  give  a  larger  pulse,  and,  if  possible, 
less  disturbance  by  movement  of  the  chest  walls.  The  subject  was  sleeping  lightly 
during  this  extract.  From  o  to  &  the  kymograph  was  run  rapidly  to  show  the 
pulse  form.  There  are  several  Traube-Hering  waves  in  the  brain  record.  At 
times  there  is  a  suggestion  of  such  a  wave  in  the  jugular.  But  the  wave  in  the 
jugular  is  not  parallel  with  that  in  the  brain.     Thus  c  marks  a  crest,  and  d  a 

62 


THE  JUGULAR  PULSE  63 

trough  in  the  venous  curve.  And  c  is  just  before  a  trough  in  the  brain;  d  is 
slightly  before  a  crest  in  the  brain. 

H.,  July  26,  V  (Fig.  72,  Plate  56). — As  in  the  above  records,  the  brain  curve 
is  at  the  bottom  and  was  taken  w^ith  the  first  form  of  brain  plethysmograph.  The 
subject  had  been  asleep  but  w^as  beginning  to  be  restless.  This  extract  shows  the 
largest  reactions  in  the  jugulars  that  I  have  obtained  in  any  record.  Periods  of 
restricted  breathing  and  rising  brain  volume  alternated  with  periods  of  freer 
breathing  and  falling  brain  volume.  An  irregular  heart-beat  interferes  with 
the  evenness  of  the  record.  The  brain  curve  a  little  after  h  is  obscured  by  the 
fact  that  the  needle  was  accidentally  moved  just  as  the  fall  was  beginning.  As  a 
consequence,  the  piston  had  to  be  raised  artificially.  At  (5,  the  subject  moved. 
The  jugular  curve  shows  marked  reactions,  but  they  are  not  parallel  to  those  in 
the  brain.  At  a,  6,  and  c,  the  fall  of  the  brain  tracing  is  accompanied  by  a  distinct 
rise  in  the  jugular.  The  return  to  normal  was  gradual.  There  was  no  sustained 
inspiratory  position,  so  that  these  changes  were  probably  not  due  to  movement 
of  the  chest  wall.  Possibly  the  increased  breathing  activity,  especially  in  the 
abdomen,  caused  an  inrush  of  blood  into  the  chest ;  and  changed  heart  action  may 
have  played  some  part.  In  any  case,  the  response  in  the  venous  system  could  not 
have  been  responsible  for  the  reactions  shown  in  the  brain  curve. 

I  shall  not  reproduce  any  of  the  records  of  going  to  sleep,  since  they  were 
long  and  show  no  measurable  change  in  the  jugular. 

H.,  July  I/,  IV  (Fig.  yT„  Plate  56). — In  all  the  records  we  have  been  describ- 
ing, the  subject  was  lying  down  on  his  back.  This  is  an  extract  taken  from  an 
experiment  in  which  the  subject  was  sitting  propped  up.  The  second  form  of 
brain  plethysmograph  was  used.  The  kymograph  was  running  rapidly.  The 
jugular  cup  was  in  the  same  position  in  which  it  had  been  used  a  few  minutes 
before  when  a  good  venous  pulse  had  been  obtained  with  the  subject  lying  down. 
The  brain  tracing  is  at  the  bottom.  It  will  be  seen  that  only  an  imperfect  form 
of  carotid  pulse  was  given  in  place  of  the  jugular. 

The  diameter  of  the  record  is  reduced  one-half  in  the  reproduction. 

This  test  was  tried  several  times  and  with  every  possible  position  of  the  receiv- 
ing cup.  Nothing  but  an  arterial  pulse  was  ever  found,  except  when  the  subject 
was  lying  down. 

The  study  of  the  venous  system  has  yielded  mostly  negative  results.  I  wil! 
suggest  that  the  Traube-Hering  wave  found  may  be  an  arterial  wave  from  the 
neighboring  tissues.  In  a  few  cases,  it  is  more  nearly  parallel  to  the  brain.  On 
this  account,  as  well  as  because  of  its  relation  to  certain  emotions,  it  is  desirable 
that  the  circulation  in  the  head  and  neck  be  more  fully  investigated. 


CHAPTER  VI 
THE   PULSE  FORM 

It  is  my  purpose  in  this  section  to  bring  together  several  facts  concerning 
changes  in  pulse  form,  mainly  in  the  brain,  which  have  revealed  themselves  in, 
the  various  records.  They  will,  I  think,  aid  somewhat  in  the  interpretation  of  the 
reactions  in  the  brain,  and  also  of  the  causes  of  pulse  form  in  general.  I  shall 
first  reproduce  and  describe  a  number  of  extracts  from  different  records.  Only  a 
large  enough  portion  will  be  given  in  each  case  to  bring  out  the  pulse  form  clearly. 

J.,  December  i,  I  (Fig.  74,  Plate  57). — This  shows  the  pulse  form  from  the 
brain  of  the  first  subject  when  he  was  lying  down  on  his  back.  The  dicrotic 
notch  and  wave  are  low.  The  primary  wave  is  comparatively  high,  with  steep 
rise  and  fall.  This  should  be  compared  with  the  curves  already  described,  from 
the  first  subject  lying  down.  November  28,  III  (Fig.  35,  Plate  33),  shows  about 
the  highest  dicrotic  I  have  seen  from  the  brain  of  the  first  subject  under  these 
conditions  (awake  lying  down).  In  the  records  of  waking  reactions  lying  down, 
it  will  be  seen  that  the  dicrotic  notch  is  often  the  lowest  point  in  the  wave.  This 
is  a  very  common  occurrence.  Furthermore,  reactions  to  stimuli  lying  dawn  very 
seldom  caused  a  rise  in  the  dicrotic.  Practically  the  only  cases  that  did  this,  show 
a  rounded  pulse  like  that  always  obtained  by  plugging  the  trephine. 

On  the  other  hand,  examination  of  such  curves  as  those  from  February  20 
(Plates  2  to  7),  especially  IV,  no.  i  (Plate  6),  where  the  drum  was  running 
rapidly,  shows  that  as  the  subject  went  to  sleep,  the  dicrotic  notch  and  wave  were 
markedly  raised  in  position.     They  were  depressed  again  with  awakening. 

/.,  November  16,  II,  no.  i  and  no.  2  (Fig.  74,  Plate  57). — These  are  from  the 
first  subject  sitting  up  nearly  erect.  In  no.  i  he  was  awake,  in  no.  2  he  had  gone 
to  sleep  lightly.  It  will  be  seen  that  even  when  awake,  the  dicrotic  is  rather  high 
in  position.  But  when  he  goes  to  sleep,  it  is  still  more  elevated,  often  to  the  level 
of  the  primary  wave.  The  magnifying  glass  also  shows  in  many  cases  a  pre- 
dicrotic  wave. 

J.,  December  19,  III,  no.  i  and  no.  2  (Fig.  74,  Plate  57). — These  are  from  the 
first  subject  sitting  propped  up.  In  no.  i  he  was  awake.  The  dicrotic  position 
is  medium.  After  going  to  sleep,  the  pulse  became  so  large  that  the  kymograph 
had  to  be  run  rapidly  in  order  to  show  the  form.  No.  2  is  an  extract  containing 
two  of  the  waves  obtained  in  this  way,  immediately  following  a  reference  line. 
The  dicrotic  notch  and  wave  are  more  prominent  and  much  elevated  in  position. 

Reference  should  be  made  also  to  the  records  reproduced  above,  especially 
February  6,  II,  no.  i  (Plate  19)  and  no.  2  (Plate  19)  and  January  30,  III  (Plate 
18),  and  to  those  on  waking  reactions  published  in  my  previous  work.  A  careful 
examination  of  all  curves  taken  for  reactions  to  stimuli  while  awake  sitting  up, 

64 


THE  PULSE  FORM  6S 

shows  that  the  dicrotic  was  sometimes  sHghtly  lowered,  sometimes  slightly  raised, 
but  usually  not  definitely  changed  with  the  reactions. 

H.,  November  lO,  IV,  no.  i  and  no.  2  (Fig.  74,  Plate  57). — These  are  from  the 
second  subject  using  the  first  form  of  brain  plethysmograph.  He  was  drowsy 
but  not  asleep.  In  no.  i  he  was  lying  down  on  his  back.  Immediately  afterward 
be  turned  his  head  somewhat  to  the  right,  and  no.  2  shows  the  condition  then. 
The  dicrotic  was  lowered  in  the  position  to  the  right. 

H.,  November  10,  I  (Fig.  74,  Plate  57). — The  subject  (second)  was  lying  on 
his  right  side  and  was  awake.  The  kymograph  was  run  more  rapidly.  The  first 
form  of  brain  plethysmograph  was  used.  The  dicrotic  was  very  low.  But  in 
most  records  taken  under  the  same  conditions,  it  is  even  lower.  This  shows  about 
the  highest  dicrotic  found  in  the  second  subject  lying  on  his  right  side  awake. 

H.,  May  16,  II,  no.  i  and  no.  2  (Fig.  74,  Plate  57). — These  are  from  the  second 
subject  awake  using  the  first  form  of  brain  plethysmograph.  He  was  lying  down 
on  his  back.  In  no.  i  his  head  was  turned  a  little  to  the  right  of  the  vertical,  in 
no.  2  it  was  turned  as  much  to  the  left.  The  pulse  became  larger  and  the  dicrotic 
more  prominent  and  more  elevated. 

H.,  May  3,  I,  no.  i  and  no.  2  (Fig.  75,  Plate  58). — The  subject  (second)  was 
lying  down  on  his  back,  and  the  first  form  of  brain  plethysmograph  was  used. 
In  no.  I  he  was  awake,  in  no.  2  he  was  asleep.  The  pulse  became  larger  with 
sleep,  and  the  dicrotic  notch  and  wave  became  much  more  prominent  and  elevated. 
There  is  a  distinct  predicrotic  wave. 

H.,  April  6,  II,  no.  5  and  no.  4  (Fig.  75,  Plate  58). — These  are  further  ex- 
tracts from  the  series  of  April  6,  of  which  several  have  already  been  studied.  All 
were  taken  from  the  second  subject  lying  on  his  back  and  using  the  first  form 
of  brain  plethysmograph.  The  kymograph  was  run  rapidly  to  show  pulse  form. 
In  no.  3  the  subject  was  asleep;  no.  4  was  taken  later  in  the  same  record  when  the 
subject  had  awakened.  With  awakening,  the  dicrotic  became  much  depressed, 
but  the  dicrotic  notch  was  not  so  low  as  when  the  subject  was  lying  on  his 
right  side. 

H.,  November  10,  III,  no.  i  and  no.  2  (Fig.  75,  Plate  58). — The  subject 
(second)  was  lying  down  on  his  back  with  his  head  turned  to  the  right,  and  using 
the  first  form  of  brain  plethysmograph.  In  no.  i  he  was  awake,  in  no.  2  he  had 
gone  to  sleep.  When  awake  the  dicrotic  was  extremely  low  and  almost  elimi- 
nated. With  sleep  the  pulse  became  larger,  the  dicrotic  notch  and  wave  distinctly 
higher  and  more  prominent. 

H.,  February  16,  I  (Fig.  75,  Plate  58). — The  conditions  were  similar  to  those 
in  November  10,  III.  The  subject  would  go  partly  asleep  with  restricted  breath- 
ing and  rising  brain  volume  and  then  awaken  with  freer  breathing  and  falling 
brain  volume.  This  extract  begins  with  a  period  of  disturbance  and  low  volume, 
and  ends  with  a  period  of  light  sleep  and  higher  volume.  The  rise  of  volume  is 
accompanied  by  a  somewhat  more  elevated  dicrotic.  All  such  periods  showed  at 
least  as  much  of  a  change  as  this,  many  of  them  more. 

Examination  of  the  pulse  form  in  the  records  from  the  second  subject  which 

6 


66  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

are  reproduced  in  the  preceding  chapters,  agrees  in  every  way  with  the  changes 
found  here.  The  dicrotic  is  depressed  when  the  head  is  turned  to  the  right, 
relatively  elevated  when  the  head  is  lying  on  its  back.  Sleep  in  any  position  gives 
a  higher  and  more  prominent  dicrotic  than  the  waking  condition  in  the  same 
position.  When  the  second  form  of  brain  plethysmograph  was  used,  the  pulse 
form  was  sometimes  modified  by  approach  to  an  upper  limiting  line.  Such  a 
restriction  will  always  tend  to  reduce  all  waves  to  the  same  level  and  give  a  more 
blunted  or  rounded  pulse.  But  such  curves  as  H.,  January  25,  II  (Plate  16), 
show  that  there  is  a  lower  dicrotic  with  waking  conditions  where  there  is  no 
question  of  interference  by  a  limiting  line. 

H.,  July  21,  nos.  2,  4,  5,  7,  8  (Fig.  76,  Plate  59)  and  11  (Fig.  y-j,  Plate  60). — 
This  series  of  records  was  taken  from  the  second  subject  in  midday  and  while  he 
was  thoroughly  awake.  The  second  form  of  brain  plethysmograph  was  put  on 
and  the  subject  lay  down  on  his  back.  His  legs  rested  on  the  bed,  and  his  body 
and  head  rested  on  a  wide  board  without  even  a  pillow  under  his  head.  A  curve 
was  taken  in  this  position.  Then  the  head-end  of  the  board  was  raised  about  five 
degrees  and  another  curve  was  taken ;  the  head-end  was  again  raised  five  degrees 
and  another  curve  taken,  and  so  on  until  eleven  curves  had  been  taken.  With 
each  curve  the  drum  was  run  rapidly,  and  a  time  marker  writing  fiftieths  of  a 
second  was  used.  Five  successive  pulse-beats  from  each  curve  were  then  selected. 
The  beginning  of  each  pulse,  and  the  crest  and  trough  of  the  first  three  waves  in 
each  pulse  were  marked  as  carefully  as  possible.  The  crests  and  troughs  were 
determined  by  laying  a  line  along  the  rises  and  falls  and  marking  the  turning 
points.  Points  half  way  between  the  turning  points  were  taken  as  the  points 
desired.  These  points  were  then  reduced  to  the  level  line  and  marked  upon  the 
time  tracing  by  a  process  similar  to  that  used  in  studying  transmission  times. 
The  times  from  the  beginning  of  the  pulse  to  the  first  crest,  from  the  first  crest  to 
the  first  trough  and  so  on  to  the  third  crest,  were  counted  in  fiftieths  of  a  second. 

Further,  a  strip  of  transparent  celluloid,  on  which  lines  were  ruled  one 
millimeter  apart,  was  taken  and  one  line  laid  down  connecting  the  beginning  and 
end  of  the  pulse-beat.  Using  this  line  as  a  base,  the  distances  up  to  the  first 
crest,  the  first  trough,  the  second  crest,  the  second  trough,  and  the  third  crest 
were  counted.  I  then  averaged  the  corresponding  quantities  for  each  curve.  I 
will  quote  three  typical  sets  of  averages.  In  each  set,  the  first  quantity  given  is 
the  pulse  length,  the  second  outside  of  parentheses  is  the  time  from  the  beginning 
of  the  pulse  to  the  first  crest,  the  third  outside  of  parentheses  is  the  time  from 
the  first  crest  to  the  first  trough,  and  so  on  to  the  time  from  the  second  trough  to 
the  third  crest.  The  quantities  in  parentheses  are  the  elevations  of  the  same 
points.  The  first  quantity  in  brackets  is  the  total  time  from  the  beginning  of  the 
pulse  to  the  crest  of  the  second  wave,  and  the  second  in  brackets  is  the  total  time 
to  the  crest  of  the  third  wave.  Curve  4  gave  44.4,  5.5  (4),  3.8  (2.1),  4.1  (3.1), 
[13.4],  3  (2.2),  5.1  (2.9),  [21.4].  Curve  7  gave  43.5,  5.5  (28.8),  4  (18.8), 
3-9  (23),  [134],  3-4  (20.2),  5.3  (21),  [22.1].  Curve  11  gave  44.5,  6.1  (33.5). 
3.4  (27),  4.2  (35.3),  [13.7],  3.4  (30.5),  4.8  (30.7),  [21.9]. 


THE  PULSE  FORM  67 

I  reproduce  a  set  of  typical  pulses  from  six  curves.  No.  2  contains  part  of 
those  marked  to  count.  But,  as  a  rule  the  record  was  too  much  marred  by  the 
instruments  to  be  reproduced,  and  other  parts  were  selected  to  be  printed.  It  will 
be  seen  from  the  measurements  and  from  the  tracings  that  the  different  crests 
were  slightly  delayed,  if  anything,  as  the  subject  was  raised  toward  a  sitting  posi- 
tion, but  there  was  no  important  variation  in  temporal  arrangement.  The  height 
of  the  pulse  became  greatly  increased,  the  height  of  the  secondary  waves  from 
trough  to  crest  did  not  increase  in  proportion  to  the  increase  in  the  pulse,  in  fact, 
the  second  trough  and  following  wave  became  even  less  prominent.  The  main 
skeleton  of  the  pulse  on  which  the  secondary  waves  may  be  considered  erected, 
seems  to  be  more  rounded  out  when  the  subject  is  sitting  up,  instead  of  being 
turned  sharply  downward  immediately  after  the  primary  thrust  as  it  is  when  the 
subject  is  lying  down,  especially  when  he  is  lying  on  his  right  side. 

H.,  August  I,  II,  and  H.,  July  26,  II  (Fig.  yy,  Plate  60). — These  were  taken 
from  the  second  subject  by  means  of  the  first  form  of  brain  plethysmograph.  He 
was  sitting  up  leaning  forward.  The  various  troughs  and  crests  are  not  clear  in 
H.,  July  26,  II.  But  the  general  similarity  of  form  to  the  above  curves  from  the 
sitting  up  position  is  evident. 

H.,  July  26,  I,  no.  i  and  no.  2  (Fig.  TJ,  Plate  60). — The  second  form  of  brain 
plethysmograph  was  used.  In  no.  i  the  subject  was  lying  down  on  his  back  and 
resting  his  head  on  a  pillow  of  medium  thickness.  In  no.  2,  his  head  was  raised 
up  at  a  sharp  angle  with  his  body.  There  is  an  elevation  of  the  secondary  waves, 
only  of  less  degree  than  when  his  body  was  raised  for  the  records  of  July  21. 

With  the  second  subject  sitting  up,  the  elevation  of  the  secondary  waves  is 
already  so  extreme  that  the  change  on  going  to  sleep  cannot  show  itself  so  clearly 
as  with  the  first  subject.  But,  on  the  whole,  the  tendency  is  toward  a  still 
greater  elevation. 

Recently  I  have  used  a  third  trephined  subject  K.  in  a  few  experiments.  The 
work  was  mostly  concerning  the  effects  of  drugs  upon  the  brain  circulation.  But 
I  wish  to  refer  here  to  some  changes  of  pulse  form  in  different  positions.  The 
trephine  was  through  the  front  part  of  the  left  temporal  bone.  The  first  form  of 
brain  plethysmograph  was  used.  K  i  (Fig.  78,  Plate  61)  shows  the  pulse  when 
the  subject  was  sitting  up  with  his  head  erect.  In  K  2  (Fig.  78,  Plate  61)  he  was 
sitting  up  with  his  head  tipped  as  far  as  possible  towards  his  right  shoulder.  K  5 
(Fig.  78,  Plate  61)  is  from  a  position  sitting  up  with  his  head  tipped  toward  the 
left  shoulder.  With  K  7  (Fig.  78,  Plate  61)  he  was  lying  down  on  his  back. 
K  8  (Fig.  78,  Plate  61)  shows  the  form  when  he  was  lying  down  on  his  right  side. 
K  f  (Fig.  78,  Plate  61)  was  taken  during  another  day's  work  when  the  pulse  from 
other  positions  (all  positions  were  not  taken  on  any  one  day)  was  much  larger 
than  in  the  above  extracts.  The  subject  was  lying  on  his  left  side,  and  an  assistant 
(Dr.  Clarke)  held  his  head  so  that  it  did  not  rest  on  the  plethysmograph.  The 
tracing  shows  a  low  dicrotic  and  the  broadened,  rounded  crest  which  a  plugged 
trephine  always  tends  to  cause. 

It  is  found,  then,  that  the  effect  of  position  is  in  the  same  direction  as  in  the 


68  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

first  and  second  subjects.  The  subjects  differ  from  each  other  in  the  exact  pulse 
form  in  any  given  position,  and  each  subject  may  show  a  somewhat  different 
form  at  different  times.  But  every  change  that  amounts  to  a  lowering  of  position 
and  the  kind  of  congestion  that  results  from  lower  position,  tends  to  lower  the 
level  of  the  secondary  waves.  Any  rise  of  position  in  any  way,  causes  a  rise 
of  the  secondary  waves. 

It  may  be  added  that  a  change  of  pulse  form  due  to  position  or  sleep  lasts  as 
long  as  the  condition  which  brings  it  about. 

B.,  June  21,  no.  i  and  no.  2  (Fig.  79,  Plate  61). — These  are  from  the  subject  B.- 
immediately  after  a  blood-pressure  test.  The  lower  curve  is  a  plethysmographic 
record  from  the  right  hand,  which  had  been  running  continuously  and  with  no 
definite  change  of  level,  or  shape  and  size  of  pulse,  during  the  whole  experiment. 
The  upper  curve  is  from  the  left  wrist,  which  of  course  was  the  one  used  for 
the  blood-pressure  tracing.  No.  i  was  taken  as  soon  as  the  pressure  was  dropped 
to  zero  immediately  after  the  test.  No.  2  was  taken  about  three  minutes  later 
after  the  tingling  of  the  arm  had  ceased.  During  the  period  between  no.  i  and 
no.  2  there  was  no  measurable  change  in  the  level  or  pulse  of  the  lower  curve. 
On  the  other  hand,  the  upper  tracing  fell  six  centimeters  or  more,  and  had  to  be 
raised  artificially  several  times,  and  the  pulse  became  distinctly  smaller.  This 
decrease  of  volume  was  not  due  to  the  escape  of  venous  blood,  for  the  arterial 
pulse  should  have  increased  rather  than  decreased  in  size.  And  it  was  probably 
not  due  to  a  fall  of  blood-pressure,  for  the  other  hand  might  be  expected  to  show 
some  effects  of  such  an  extreme  fall  as  would  have  been  necessary.  We  may, 
therefore,  infer  that  we  are  dealing  with  a  condition  of  relaxation^  of  the  vessels 
of  the  left  arm  in  no.  i,  and  that  they  had  constricted  to  more  nearly  their  normal 
condition  in  no.  2.  With  the  constriction  the  dicrotic  has  fallen  and  assumed 
more  nearly  the  position  and  character  it  had  before  the  test,  which  was  approxi- 
mately like  that  of  the  lower  curve. 

W.,  July  II,  no.  I  and  no.  2  (Fig.  79,  Plate  61). — The  blood-pressure  appa- 
ratus was  used  in  another  test  that  probably  has  some  significance  for  the  explana- 
tion of  the  pulse  forms  found.  Curves  were  taken  from  the  carotid  and  from 
the  sphygmomanometer  sleeve,  along  with  a  time  record.  In  part  of  them  the 
pressure  in  the  sleeve  was  only  fifteen  millimeters;  in  others  it  was  one  hundred 
and  thirty-seven  millimeters,  which  is  a  little  above  systolic  pressure  for  the 
subject  (W.)  used.  In  the  first  case,  of  course,  the  sleeve  gave  what  we  have 
called  the  third  type  of  pulse,  and  in  the  second  case  it  gave  the  second  type 

The  beginning  of  each  pulse,  the  crest  of  the  primary  wave,  and  the  dicrotic 
notch  were  carefully  marked  on  both  curves.  The  points  were  then  reduced  to 
level  and  counted  on  the  time  line  as  before,  and  the  comparative  time  of  each 
point  in  the  carotid  and  the  sleeve  was  determined.  These  times  expressed  in 
two-hundredths  of  a  second,  were  averaged.  It  was  found  that  when  the  pressure 
in  the  sleeve  was  15  mm.,  the  beginning  of  the  pulse  in  the  sleeve  was  delayed  9.3, 

1  We  should,  doubtless,  refer  this  to  the  effects  which  asphyxia!  products  have  been  shown 
to  have  upon  the  vessels. 


THE  PULSE  FORM  69 

the  crest  of  the  wave  in  the  sleeve  was  delayed  4.5,  and  the  dicrotic  notch  in  the 
sleeve  was  delayed  8.2,  compared  with  the  carotid.  On  the  other  hand,  when  the 
pressure  was  137  mm.,  the  delay  of  the  beginning  was  9.3,  of  the  crest  was  2.8, 
and  the  dicrotic  (if,  indeed,  this  should  be  called  dicrotic)  notch  in  the  sleeve 
preceded  the  dicrotic  notch  in  the  carotid  by  5.9.  Also,  the  time  from  the  begin- 
ning of  the  pulse  to  the  dicrotic  notch  in  the  sleeve  curve,  was  counted  in  fiftieths 
of  a  second.  This  time  was  15.5  fiftieths  when  the  pressure  was  15  mm.,  and  was 
12  fiftieths  when  the  pressure  was  137  mm.  The  waves  begin  at  about  the  same 
time  with  the  two  pressures ;  but  the  crest  is  somewhat,  and  the  dicrotic  notch  is 
very  much  hastened  by  the  high  pressure. 

No.  I  shows  a  pulse  with  low  pressure  in  the  sleeve ;  no.  2  a  pulse  with  high 
pressure  in  the  sleeve.  It  will  be  seen  that  with  low  pressure  the  dicrotic  notch 
is  fairly  high  and  the  pulse-wave  falls  gradually;  while  with  high  pressure,  the 
dicrotic  notch  is  as  low  as,  or  lower  than  the  beginning  and  end  of  the  pulse. 

I.  t.  (Fig.  79,  Plate  61)  is  not  a  pulse-beat.  The  curve  is  intended  to  suggest 
the  amount  of  inertia  we  must  allow  for  in  a  pulse  form  tracing.  The  level  was 
suddenly  raised  by  driving  in  the  plunger  used  for  artificial  regulation.  The 
piston  recorder  needle  rose  more  rapidly  than  it  is  forced  to  move  in  the  usual 
pulse  curve.  The  amount  of  inertia  is  not  sufficient  to  interfere  seriously  with 
any  conclusion  we  shall  draw  as  to  pulse  form.    R.  L.  is  a  reference  line. 

The  real  summary  of  this  chapter  will  come  out  in  connection  with  a  discussion 
of  general  conclusions  in  the  next  chapter,  and  some  attempt  will  be  made  to 
explain  the  pulse  forms. 

I  may  add  that  measurement  on  the  time  line  showed  that  the  temporal  position 
of  the  secondary  waves  within  the  pulse  from  the  brain  is  about  the  same  during 
sleep  as  during  waking;  if  there  is  any  difference,  it  is  slightly  later. 


CHAPTER  VII 
GENERAL  CONCLUSIONS  AND  THEORY 

It  is  not  my  purpose  to  review  and  discuss  the  exceedingly  voluminous  litera- 
ture concerning  some  of  the  topics  considered.  I  wish  simply  to  bring  out  several 
conclusions  that  seem  to  me  justified  by  the  results  of  this  investigation. 

Huber,  Hunter  and  others  have  shown  that  there  are  nerve  terminals  in  the 
brain  vessels.  But  it  has  been  suggested  that  these  may  be  sensory  in  their  nature ; 
and,  in  any  case  their  mere  presence  does  not  necessitate  an  effective  activity. 
Wiggers  has  studied  the  brain  in  the  detached  head  of  a  dog,  by  use  of  an  im- 
proved perfusion  method.  He  found  that  certain  drugs,  especially  adrenalin, 
caused  a  change  in  the  outflow.  Since  adrenalin  probably  acts  only  upon  the  nerve 
terminals,  this  fact  indicates  the  action  of  sympathetic  fibers  in  the  brain  vessels. 
He  also  found  that  electrical  stimulation  of  the  sheath  of  the  carotid  gave  a 
decreased  outflow,  which  shows  that  constrictor  fibers  run  with  this  artery  to  the 
cerebral  vessels.  These  results  lead  us  to  look  for  more  active  control.  So  far 
as  we  are  concerned  with  the  explanation  of  the  sleep  process  and  the  effective 
control  of  the  brain  circulation,  however,  Wiggers'  work  is  insufficient  in  two 
respects.  In  the  first  place,  we  cannot  say  to  just  what  degree  the  facts  in  the  case 
of  the  dog  are  true  in  the  case  of  man.  In  the  second  place,  attempts  to  demon- 
strate the  activity  of  vaso-motor  nerves  in  the  brain  vessels,  when  the  brain  was 
under  the  influence  of  the  general  circulation,  have,  according  to  most  observers, 
ended  in  negative  results.  We  do  not  know  therefore,  to  what  extent,  if  any, 
there  may  be  effective  activity  of  cerebral  vaso-motors  under  normal  conditions. 
It  is  exactly  on  this  point  that  the  results  of  this  research  seem  to  me  to  offer 
fairly  definite  and  conclusive  evidence.  I  do  not  see  how  we  can  avoid  the 
conclusion  that  the  brain  vessels  are  not  inactive,  that  they  do  not  follow  passively 
the  changes  in  general  arterial  and  venous  pressure,  but  that  on  the  contrary,  they 
are  under  the  quite  definite  control  of  a  system  of  vaso-constrictors,  and  the  center 
of  this  control  is  probably  a  portion  of  the  general  constrictor  center  in  the 
medulla. 

In  the  first  place,  we  find  with  sleep  a  sustained  and  marked  increase  in  volume 
of  the  brain  accompanying  a  fall  of  general  arterial  pressure,  and  the  reverse 
changes  with  awakening.  Both  the  direct  blood-pressure  measurements  and  the 
study  of  transmission  times  show  this  fact.  There  are  several  reasons  for  decid- 
ing that  this  change  in  volume  cannot  be  venous  congestion.  Firstly,  there  is  no 
analogous  change  in  the  jugular  curve.  Secondly,  the  first  form  of  brain  plethys- 
mograph  gives  the  above  result  in  all  positions  with  even  greater  clearness  than 
the  second  form ;  and  this  with  a  pressure,  due  to  tension  of  the  rubber,  which  is 
higher  than  any  pressure  from  venous  congestion  could  probably  ever  attain. 

70 


GENERAL  CONCLUSIONS  AND  THEORY  7^ 

Venous  congestion  could  not  ordinarily  have  overcome  the  tension  of  the  rubber, 
which  was  far  above  the  usual  venous  pressure.  Thirdly,  the  rise  of  volume  with 
sleep  is  accompanied  by  an  increase  in  the  size  of  arterial  pulse  in  the  brain; 
the  fall  of  volume  with  waking  is  accompanied  by  a  decreased  size  of  pulse  in 
the  brain,  while  the  rise  of  brain  volume  due  to  compression  of  the  jugulars  is 
accompanied  by  a  decreased  arterial  pulse  in  the  brain.  Fourthly,  the  pressure 
in  the  jugulars  was  insufficient  to  give  any  trace  of  a  venous  pulse  when  the 
subject  was  sitting  propped  up,  or  when  he  was  sitting  up  leaning  forward;  and 
yet,  in  both  positions,  and  with  both  forms  of  brain  plethysmograph,  the  brain 
showed  the  same  reactions  in  volume  and  size  of  pulse,  as  when  the  subject  was 
lying  down. 

Disturbances  during  sleep  result  in  a  rise  of  pressure  with  a  fall  of  brain 
volume  and  decreased  size  of  pulse  from  the  brain;  again,  the  blood^pressure 
measurements  and  the  study  of  transmission  times  agree  in  this  conclusion. 
Furthermore,  with  the  second  subject,  the  Traube-Hering  wave  in  the  brain  is 
opposed  to  the  wave  in  general  arterial  pressure,  and  the  breathing  wave  is  at 
least  partly  so.  For  reasons  similar  to  those  above,  these  volume  changes  cannot 
be  venous.  The  pulse  is  largest  at  the  crest  and  the  results  were  obtained 
especially  with  the  first  form  of  brain  plethysmograph.  Iif  there  is  any  change 
in  the  jugular  curve,  it  is,  in  general,  opposed  to  that  in  the  brain.  That  the 
Traube-Hering  wave  in  brain  volume  when  the  subject  is  sitting  up  is  the  same 
as  when  he  is  lying  down,  is  attested  by  the  fact  that  it  is  always  parallel  to  that 
in  the  hand. 

I  can  see  no  reasonable  escape  from  the  conclusion  that  there  is  an  active, 
effective  vaso-motor  control  of  the  brain  vessels  in  man  under  normal  conditions. 
Other  facts  indicate  the  same  thing.  With  the  first  subject  lying  down  awake, 
stimuli  gave  a  rise  of  brain  volume  and  decreased  size  of  pulse.  This  rise  was 
doubtless  a  result  of  increased  blood-pressure.  But  the  rise  with  sleep  in  the  same 
position  is  accompanied  by  an  increased  pulse.  It  does  not  seem  possible  that  the 
change  in  volume  is  due  to  the  same  factors  in  both  cases.  Furthermore,  reactions 
in  the  brain  while  awake  show  no  definite  and  consistent  change  in  pulse  form. 
Rise  of  volume  with  sleep  invariably  tends  to  cause  a  rise  in  the  level  of  the 
secondary  waves  with  no  appreciable  change  in  their  temporal  relations;  when 
the  position  of  the  secondary  waves  is  low  at  the  start,  this  rise  in  level  is  very 
marked.  The  fall  with  awakening  gives  the  opposite  result.  Now,  in  the  study 
of  pulse  forms  from  the  hand  following  blood-pressure  tests,  we  have  found  a 
condition  which  is  probably  one  of  local  relaxation  giving  a  higher  position  of  the 
secondary  waves,  and  constriction  causes  a  return  of  these  waves  to  their  original 
position.  Also,  the  most  consistent  change  in  pulse  form  that  I  have  found  with 
reactions  while  awake  was  a  lowering  of  the  position  of  the  dicrotic  in  curves 
taken  with  the  finger  plethysmograph.  This  change  was  not  always  found,  but 
often  was.  In  this  instrument  more  than  anywhere  else  we  probably  have  a  vaso- 
constriction of  the  small  arteries  with  comparatively  little  interference  of  the 
larger  vessels  which  do  not  constrict.     An  explanation  of  these  form  changes. 


72  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

and  a  discussion  of  their  relation  to  those  found  in  different  positions,  will  make 
the  matter  clearer;  but  a  comparison  of  the  facts  stated,  certainly  suggests  that 
local  constriction  gives  a  lower  level  of  secondary  waves;  local  dilation  gives  a 
higher  level,  and  therefore  the  brain  vessels  relax  with  sleep  and  actively  constrict 
with  awakening.  All  the  facts  without  exception  consistently  lead  to  this 
conclusion. 

We  might  raise  the  question  whether  this  definite  relaxation  with  sleep,  and 
constriction  with  awakening  can  be  brought  about  in  any  way  by  the  changed 
breathing.  We  shall  discuss  the  periodic  alternation  of  restricted  and  freer 
breathing  in  connection  with  the  Traube-Hering  wave.  In  the  second  and  third 
types,  the  depth  of  breathing  was  a  little  increased,  if  anything,  in  sleep,  and  there 
was  regular  snoring  in  the  second.  But  artificial  increase  in  depth,  and  snoring 
during  the  waking  condition  gave  a  fall  of  the  brain.  The  mere  change  from 
abdominal  to  chest  breathing  causes  no  change  in  the  brain.  Changed  condition 
of  the  blood  from  changed  breathing,  if  there  is  any  such  change,  is  doubtless  not 
in  any  way  responsible. 

We  found  in  the  study  of  volume  changes,  that  the  brain  curve  was  often 
held  up  or  even  raised  a  little  for  a  few  pulse-beats  before  a  fall  in  response  to 
a  disturbance  or  awakening.  Likewise,  in  the  study  of  blood-pressure  and  of 
transmission  times,  it  was  in  the  majority  of  cases  seen  that  the  rise  of  blood- 
pressure  began  one  or  two  pulse-beats  before  the  fall  of  brain  volume.  These 
facts  indicate  that  the  reaction  time  of  the  brain  vessels  is  distinctly  longer  than 
that  of  the  main  vaso-motor  mechanisms  outside  the  brain.  The  cause  of  the 
temporary  hold-up  and  of  the  rise  of  pressure  before  the  fall  in  the  brain  begins, 
is  to  be  found  in  the  quicker  response  of  the  other  regions.  We  have  an  analogous 
case  in  the  fact  that  there  is  often  a  rise  with  smaller  pulse,  in  the  hand  for  three 
or  four  pulse-beats  before  the  fall  begins  in  response  to  very  strong  stimuli  while 
the  subject  is  awake.  We  may  suppose  that  both  hand  and  brain  react  more 
slowly  than  the  great  splanchnic  area,  the  brain  most  slowly  of  all,  perhaps.  It 
should  be  stated  that  the  change  in  either  hand  or  brain  may  sometimes  begin 
before  the  rise  in  blood-pressure. 

A  comparison  of  the  reactions  to  stimuli  while  the  subject  is  asleep  and  while 
he  is  awake,  brings  out  an  interesting  difference  between  the  vaso-motor  control 
in  the  brain  and  in  the  periphery.  Disturbances  while  asleep  consistently  give  a 
fall  in  the  brain  which  we  have  shown  to  be  due  to  vaso-constriction.  Dis- 
turbances while  awake  consistently  give  a  rise  of  volume  of  the  brain,  although 
the  effect  was  not  so  great  in  the  second  subject  as  in  the  first.  These  statements 
hold  in  all  positions  of  the  subjects  and  in  curves  with  either  form  of  brain 
plethysmograph.  When  the  subject  is  sitting  up,  this  increase  during  waking 
condition  is  accompanied  by  increased  pulse,  but  neither  the  reactions  while  awake 
sitting  up  nor  those  while  awake  lying  down,  give  the  characteristic  pulse  form 
changes  of  sleep.  Neither  the  reaction  while  asleep  nor  that  while  awake  can  be 
due  to  venous  congestion,  and  yet  the  cause  of  the  one  must  be  different  from  that 
of  the  other    Doubtless,  the  main  or  only  factor  in  the  increase  while  awake  is 


GENERAL  CONCLUSIONS  AND  THEORY  73 

the  rise  of  blood-pressure  which  is  brought  about  by  constriction  of  other  regions. 
The  pulse  does  not  increase,  usually  decreases  while  lying  down  because  the 
vessels  are  approaching  a  practical  limit  of  distensibility.  We  noticed  also  that 
the  pulse  is  generally  smaller  during  the  first  part  of  a  reaction  period  while 
awake,  than  it  is  at  the  same  level  of  volume  during  the  last  part.  We  might  go 
farther  and  infer  with  some  probability  that  there  is  a  tendency  of  the  brain 
vessels  to  constrict  and  lower  the  limit  of  distensibility  during  reactions  while 
awake,  especially  at  first;  but  this  tendency  is  overcome  by  the  rise  of  general 
arterial  pressure. 

We  reach  the  conclusion,  then,  that  the  brain  vessels  relax  on  going  to  sleep 
and  constrict  on  awakening  with  relatively  great  activity.  There  is  a  fall  even 
when  the  subject  is  awakened  with  a  start  by  a  strong  stimulus,  and  in  spite  of  a 
large  rise  of  blood-pressure.  Correspondingly,  few  reactions  while  awake  even 
compare  with  the  rise  with  going  to  sleep.  On  the  other  hand,  the  ordinary 
stimuli  of  the  waking  condition  seem  sufficient  to  cause  the  brain  to  constrict 
nearly  to  its  limit,  and  to  remain  in  that  condition ;  so  that  the  tendency  to  further 
constriction  with  stimuli  while  awake  is  relatively  powerless  and  is  overcome  by 
the  rise  of  pressure  due  to  constriction  of  other  regions  which  do  not  show  such  a 
limit  of  constriction. 

The  increase  in  brain  volume  due  to  holding  the  breath  and  the  decrease  due  to 
increased  breathing  are  probably  primarily  the  results  of  changes  in  general 
arterial  pressure.  I  have  not  evidence  enough  to  say  what  local  activity  may  be 
present,  and  this  subject  deserves  further  study  as  soon  as  there  is  opportunity. 

It  has  been  suggested  that  the  vaso-motors  in  the  brain  may  react  differently 
in  different  areas  according  to  the  nature  of  the  stimulus  and  consequent  activity 
of  the  different  parts.  This  can  only  be  determined  on  a  person  with  at  least 
two  trephines  in  different  locations.  But  I  am  inclined  to  doubt  it  because  of  the 
indications  of  some  tendency  to  constrict  in  response  to  stimuli  that  certainly 
involved  the  activity  of  the  area  under  the  trephine. 

The  respiratory  wave  in  the  brain  volume  was  found  to  be  greater  during  sleep 
than  during  the  waking  condition,  and  greater  with  snoring  than  with  freer 
breathing.  There  is  a  large  breathing  wave  in  the  heart-rate,  the  increase  in  rate 
beginning  soon  after  the  beginning  of  inspiration,  the  decrease  in  rate  beginning 
soon  after  the  beginning  of  expiration.  The  blood-pressure  tests  (and  with  less 
certainty  the  transmission  time  tests)  showed  that  the  respiratory  wave  in  blood- 
pressure  begins  its  rise  anywhere  on  the  rise  of  volume.  In  many  records  the 
rise  in  pressure  begins  just  before  the  crest  of  volume,  and  the  greater  part  of  the 
rise  in  pressure  coincides  with  a  falling  volume,  lit  seems  possible  that  the 
trough  of  pressure  more  nearly  corresponds  to  the  trough  of  volume  during  sleep 
than  during  waking  condition.  I  cannot  avoid  the  conclusion  that  vaso-motor 
changes  play  an  appreciable  part  in  the  respiratory  wave,  notwithstanding  the 
usual  assumption  to  the  contrary.  Inspiration  is  the  period  of  dilation,  expiration 
is  the  period  of  constriction.  If  there  is  a  nearer  correspondence  of  pressure  and 
volume  waves  during  sleep,  it  probably  means  that  a  greater  part  is  played  by 


74  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

pressure  changes  in  the  chest  on  account  of  snoring,  and  by  the  unusually  large 
wave  in  the  heart-rate. 

It  was  found  that  the  Traube-Hering  wave  is  parallel,  or  nearly  so,  in  the 
brain  and  hand  of  each  of  the  three  trephined  subjects  used.  With  the  second 
subject,  this  wave  is  uniformly  active  in  brain  and  hand;  i.  e.,  the  fall  corresponds 
to  rising  pressure,  the  rise  corresponds  to  falling  pressure.  So  far  as  could  be 
inferred  from  the  transmission  curves,  which  were  not  very  certain,  the  wave  is 
passive  in  the  first  subject  except  when  accompanied  by  periods  of  alternately 
restricted  and  freer  breathing  in  sleep.  During  the  transition  as  the  subject  goes 
to  sleep,  the  wave  is  not  always  parallel  in  brain  and  hand.  It  is  certainly  passive 
in  one  subject  (B.) ;  and  is  partly  passive,  partly  active  in  another  (W.).  Of 
course,  in  these  cases  we  do  not  know  whether  the  waves  are  parallel  in  brain  and 
hand.  But  in  any  case,  any  investigation  which  attempts  to  establish  a  relation 
between  the  Traube-Hering  wave  and  other  phenomena  can  have  little  certainty 
without  a  blood-pressure  test  which  will  show  the  kind  of  wave  dealt  with. 

We  found  the  Traube-Hering  wave  of  the  waking  condition  giving  place  to  the 
wave  with  periodic  changes  of  breathing  during  sleep.  These  breathing  changes 
cannot  be  looked  upon  as  the  cause  of  the  volume  changes.  While  awake,  re- 
striction of  breathing  caused  a  rise  in  brain  volume  because  of  increased  blood- 
pressure,  and  deeper  breathing  caused  a  fall  because  of  the  lowered  blood- 
pressure.  In  sleep,  the  restricted  period  is  accompanied  by  relaxation  of  brain 
vessels  and  lower  blood-pressure,  and  freer  breathing  is  accompanied  by  con- 
striction in  the  brain  and  higher  blood-pressure.  Furthermore,  the  rise  of  volume 
when  the  breath  is  held  in  waking,  begins  some  time  after  the  beginning  of 
restricted  breathing,  and  it  reaches  its  crest  a  couple  or  more  breaths  after  the 
return  of  freer  breathing.  During  sleep,  the  rise  of  brain  volume  begins  early ; 
the  fall  begins  sometimes  before,  sometimes  simultaneous  with,  more  often  after 
the  abrupt  beginning  of  freer  breathing.  But  the  blood-pressure  and  transmission 
time  tests  show  that  constriction  in  other  regions  usually  begins  a  little  before  the 
brain  and  generally  as  soon  as  or  earlier  than  the  freer  breathing.  In  the  third 
type  of  breathing,  the  transition  is  more  gradual  and  the  change  in  breathing  is 
nearly  always  somewhat  delayed,  compared  with  the  corresponding  phase  of 
volume.  The  breathing  change,  therefore,  cannot  be  primary,  although  an  abrupt 
breathing  movement  may  possibly  act  like  any  other  stimulus.  Lastly,  a  vaso- 
motor wave  persists  when  the  breathing  change  is  entirely  absent.  We  must 
suppose  that  the  vaso-motor  wave  is  primary  and  the  breathing  center  is  stimulated 
by  it.  It  is  possible  that  an  accumulation  of  carbon-di-oxide  during  restricted 
breathing  tends  to  stimulate  both  centers.  The  Traube-Hering  wave  during 
waking  condition  seems  to  be  increased  by  conditions  following  inhibited  breath- 
ing. It  is  never  so  large  at  other  times  in  sleep  as  when  we  find  the  first  type  of 
breathing.  It  is  not  improbable  that  the  wave  represents  mainly  the  attempt  of 
the  vaso-motor  center  to  adapt  itself  to  chemical  stimuli  such  as  carbon-di-oxide. 
It  might  be  noted  in  this  connection  that  we  find  an  active  wave  in  the  brain 
volume  when  the  subject  is  awake,  and  an  external  stimulus  would  give  a  passive 
rise  of  volume. 


GENERAL  CONCLUSIONS  AND  THEORY  75 

The  heart-rate  curves  indicate  that  the  heart  is  accelerated  during  the  inactive 
phase  of  the  Traube-Hering  wave,  and  slowed  during  the  active  phase.  This  rela- 
tion is  probable,  although  further  work  will  be  necessary  in  order  to  speak  with 
certainty.  It  is  certain  that  we  usually  get  a  temporarily  slowed  heart  with 
periods  of  disturbance  and  freer  breathing  with  vaso-constriction ;  and  a  faster 
heart  as  a  rule  with  periods  of  restricted  breathing  and  vaso-dilation  during  sleep. 
But  during  waking  condition,  restriction  of  breathing  causes  a  slowed  heart-rate, 
and  increased  breathing  causes  a  faster  heart-rate.  It  is  probable,  then,  that  the 
vaso-motor  process  rather  than  the  accompanying  breathing  change,  is  the  cause 
of  the  corresponding  wave  in  the  heart-rate,  as  it  is,  of  course,  when  there  is 
no  change  in  the  breathing. 

It  looks  as  though  the  center  for  vaso-motor  control  in  the  brain  is  a  part  of 
the  general  center  in  the  medulla,  and  the  activities  of  the  breathing  and  vaso- 
motor centers  influence  each  other  and  also  the  inhibitory  center  of  the  heart. 
Activity  of  the  vaso-motor  center  perhaps  stimulates  both  the  others.  Activity 
(inspiratory)  of  the  breathing  center  inhibits  both  the  others. 

We  may  get  a  suggestion  for  the  explanation  of  the  pulse  form  changes  from  a 
consideration  of  the  pulse  from  the  sphygmomanometer  sleeve.  With  very  high 
pressures  in  the  sleeve,  we  found  a  small  pulse  in  which  the  fall  from  the  primary 
rise  to  the  end  was  fairly  gradual.  Von  Recklinghausen  has  explained  this  as 
due  to  the  fact  that  the  neighboring  tissues  partly  support  the  edge  of  the  sleeve 
and  enable  the  changes  in  blood-pressure  with  this  assistance  to  impress  it  as 
though  these  changes  were  slight  variations  in  the  supporting  force.  With  some- 
what lower  pressure  in  the  sleeve,  we  obtain  a  pulse  in  which  the  primary  rise  is 
quickly  followed  by  a  fall  to  a  trough  often  lower  than  the  beginning  and  end 
of  the  pulse ;  this  is  the  second  type  of  pulse.  In  the  preceding  chapter,  this  pulse 
was  compared  with  the  third  type  obtained  when  the  pressure  in  the  sleeve  is 
below  blood-pressure.  It  was  found  that  the  two  types  begin  about  the  same  time 
after  the  carotid;  and  the  dicrotic  notch  in  the  third  type  was  nearly  as  much 
after  the  corresponding  notch  in  the  carotid.  But  in  the  second  type,  the  dicrotic 
notch  preceded  the  notch  in  the  carotid,  so  that  the  length  of  the  systolic  wave  was 
shortened  by  3.5  fiftieths  of  a  second.  We  may  suppose  that  in  the  third  type  the 
wave  is  broadened  by  reflection  from  the  terminals  in  the  hand,  and  that  in  the 
second  type  this  reflected  wave  is  of  course  absent.  Such  a  factor  doubtless 
plays  a  part.  But  the  reflection  of  the  sharp  rise  of  the  systolic  wave  would  be 
mainly  concerned,  and  this  should  broaden  and  delay  the  crest  approximately  as 
much  as  it  displaced  the  dicrotic  notch.  Instead  of  this,  we  find  the  crest  hastened 
comparatively  little  in  the  second  type,  the  difference  consists  mainly  in  the  very 
rapid  fall  to  the  dicrotic  ( ?)  notch.  It  may  be  added  that  the  pulse  changes 
toward  the  third  type  when  the  pressure  is  sufficiently  relaxed  to  allow  an  inrush 
of  blood  into  the  lower  arm ;  and  yet  there  is  no  back  reflection  from  the  hand 
then,  as  shown  by  the  simple  step-up  form  of  pulse  from  the  lower  arm.  This 
fact  and  the  extremely  low  dicrotic  notch  of  the  second  type  combined  with  a 
systolic  wave  that  is  higher  than  that  in  the  first  type,  suggests  that  it  is  against 


76  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

the  clear-cut  closure  of  the  artery  by  the  sleeve  that  we  have  the  most  definite  . 
reflection.     The  momentum  of  the  primary  wave  may  raise  the  sleeve  somewhat, 
and  the  rebound  gives  a  quick  fall  to  a  very  early  and  low  dicrotic  (  ?)  notch. 

Now  we  have  found  that  constriction  in  an  area  tends  to  lower  the  level  of 
the  secondary  waves  in  the  pulse  from  that  area,  by  causing  a  quick  fall  after  the 
crest  in  the  skeleton  (omitting  secondary  waves)  form  of  the  pulse.  Relaxation 
gives  the  opposite  result.  As  I  think  of  it,  the  constriction  gives  a  higher  coefH- 
cient  of  elasticity  in  the  area  and  leads  to  a  quick  rebound  after  the  primary 
wave.  Similarly  a  lower  position  (lying  down,  etc.)  of  the  area  causes  a  local 
rise  of  pressure,  a  stretching  of  the  vessels  toward  their  limit  of  distensibility,  a 
higher  coefficient  of  elasticity  and  a  sharp  reflection  with  consequent  lowering  of 
the  latter  part  of  the  pulse.  A  higher  position  (sitting  up,  etc.)  gives  a  lowering 
of  a  coefficient  of  elasticity  in  the  area,  less  reflection,  and  therefore  a  pulse  more 
rounded  out  and  with  higher  level  of  the  secondary  waves.  When  the  change  in 
volume  is  brought  about  by  a  change  in  general  arterial  pressure,  or  even  when 
there  is  a  change  in  arterial  pressure  approximately  proportional  to  the  vaso-motor 
change,  the  coefficient  of  elasticity  outside  the  area  concerned  is  modified  also 
perhaps  even  more  than  that  in  the  area.  Under  these  circumstances  the  pulse 
form  may  not  be  definitely  changed.  It  is  the  distinct  change  in  coefficient  of 
elasticity  in  a  given  area,  compared  with  that  in  the  general  system,  that  determines 
a  marked  difference  in  reflection  and  pulse  form. 

Of  course,  other  factors,  especially  the  relative  temporal  position  of  the 
secondary  waves  within  the  total  wave,  determine  the  pulse  form  throughout  the 
system.  In  spite  of  the  excellent  arguments  of  Von  Kries,  Von  Frey  and  others, 
however,  it  seems  to  me  probable  that  reflection  influences  the  pulse  form  more  in 
the  above  way  than  by  creating  definite  secondary  waves  which  then  travel  into 
other  regions.  Von  Kries  states  that  the  tachograph  shows  greater  reflection  with 
elevation  of  the  arm.  It  seems  to  me  that  his  plates  show  less  reflection  then,  in 
proportion  to  the  previous  inflow.  The  similarity  of  my  interpretation  to  that  of 
Von  Recklinghausen  is  obvious,  although  I  did  not  know  his  work  in  time  to 
help  me  in  taking  and  working  up  my  own  records. 

Both  change  of  position  and  vaso-motor  reactions  seem  to  cause  greater  change 
in  the  pulse  form  from  the  brain  than  in  that  from  other  regions.  We  might  infer 
that  both  these  processes  give  a  greater  change  in  coefficient  of  elasticity  in  the 
brain  vessels  than  in  others ;  but  I  know  no  explanation  for  this  difference. 

According  to  the  results  of  this  investigation,  we  certainly  cannot  adopt  an 
anaemia  theory  of  sleep.  I  once  thought  it  possible  to  explain  it  as  due  to 
separation  of  dendrites  and  axones  by  expansion  of  the  cerebral  vessels.  There 
are  at  least  two  reasons  for  giving  up  this  view.  In  the  first  place,  there  are 
large  increases  in  brain  volume  with  stimuli  while  awake.  These  are  usually  less 
than  the  volume  change  with  sleep,  to  be  sure ;  but  they  are  large  enough  to  be 
significant  and  they  certainly  show  no  tendency  to  cause  sleep.  In  the  second 
place,  we  have  found  definite  evidence  that  the  circulation  change  lags  behind  the 
mental  process.     The  relaxation  of  the  brain  vessels  with  sleep,  and  their  con- 


GENERAL  CONCLUSIONS  AND  THEORY  77 

striction  with  awakening,  should  therefore  be  looked  upon  as  an  effect  rather  than 
as  a  cause  of  the  sleep  process.  We  must  make  use  of  other  facts  about  sleep  to 
find  an  explanation. 

Several  writers  have  reported  a  more  or  less  regular  curve  of  sleep.  The 
maximum  depth  is  reached  at  the  end  of  the  first  hour  or  so  after  beginning  of 
sleep;  and  then  the  curve  (representing  the  amount  of  stimulus  necessary  to 
awaken  the  sleeper)  falls  rapidly  at  first  and  slowly  later  until  awakening. 

It  is  a  frequently  stated  fact  that  the  experience  of  sleepiness  and  the  process 
of  going  to  sleep  are  subject  to  suggestion  and  to  habit.  Suggestion  means  only 
the  getting  of  an  idea  in  mind.  Probably  even  verbal  suggestion  can  sometimes 
place  a  person  in  an  attitude  favorable  to  sleep.  We  know  very  little  of  the 
circulatory  and  other  conditions  that  prevail  during  hypnotism.  So  far  as  they 
have  been  studied,  they  are  different  from  those  that  prevail  during  sleep.  But 
presumably  the  mental  content,  so  to  speak,  of  hypnotism  might  be  of  various 
kinds,  and  might  consist  of  the  experience  of  sleep  or  of  an  opposite  activity.  I 
am  inclined  to  think  that  this  subject  would  repay  investigation.  At  any  rate,  the 
oncoming  of  sleep  may  be  greatly  influenced  by  one's  surroundings.  This  does 
not  always  mean  that  sleep  is  promoted  by  withdrawing  from  external  stimuli; 
one  who  is  accustomed  to  sleep  much  under  the  influence  of  certain  external 
stimuli  may  demand  their  presence.  Sleep  is  promoted  by  the  situation  in  which 
we  have  really  become  accustomed  to  sleep.  One  may  learn  to  sleep  best  in  a 
given  environment,  just  as  one  may  learn  to  give  attention  to  anything,  or  to  work 
best  in  a  given  environment.  One  may  even  learn  to  sleep  in  a  position  which 
requires  the  continued  contraction  of  a  certain  set  of  muscles  in  order  to  maintain 
his  balance.  It  may  be  more  difficult  to  wake  up  than  to  keep  awake  sometimes^ 
just  as  it  is  difficult  to  shift  attention  when  it  is  once  absorbed  in  a  subject.  Sleep 
is  controlled  by  conditions  similar  to  those  which  control  attention  generally. 
Sleep  and  sleeplessness  are  mental  processes. 

What  then  do  we  find  if  we  attempt  to  analyze  it  introspectively  ?  Various 
people  describe  it  in  terms  that  mean  essentially  the  same  thing.  We  experience  a 
"  yielding  to  the  force  of  gravity,"  "  yielding  to  a  heaviness,"  "  becoming  lost  in 
rest  sensations  or  feelings."  These  sensations  seem  to  come  from  muscles  all 
over  the  body.  The  sensations  which  we  receive  from  the  tired  muscle  are 
undoubtedly  of  different  character  from  the  strain  sensations  we  receive  from  the 
acting  muscle.  Whether  the  two  are  due  to  different  terminals,  or  different  ways 
of  acting  of  the  same  terminals,  we  do  not  know.  The  fatigue  sensations  seem 
to  result  from  chemical  stimuli  (waste  products)  given  off  by  the  tissues.  They 
often  appear  to  be  more  intense  after  the  muscle  has  relaxed  than  before. 
Whether  the  removal  of  the  self-massage  and  the  greater  or  less  cessation  of  the 
strain  sensations  actually  allows  a  more  intense  stimulation  of  fatigue  sensations 
then,  or  whether  they  are  merely  more  noticed  then,  it  is  as  yet  difficult  to  say. 
Yoakum  points  out  that  they  develop  sooner  in  the  acting  rigid  muscle  than  in 
the  periodically  contracting  muscle.  Although  the  nerve  terminals  are  only  in 
the  muscles,  apparently,  they  may  probably  be  excited  also  by  substances  thrown 
into  the  circulation  from  other  tissues. 


78  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

As  we  go  to  sleep,  then,  we  become  absorbed  in  a  mass  or  complex  of  fatigue 
sensations.  These  tend  strongly  to  inhibit  other  processes,  especially  motor 
activity  and  consciousness  of  strain  sensations  from  the  muscles.  The  subject 
"  can't  bring  himself  to  do "  a  thing.  When  this  tendency  is  yielded  to,  the 
subjects  speak  of  the  experience  as  one  of  "  feelings  "  or  "  sensations  "  of  "  rest." 
Next,  probably  the  skin  sensations,  as  being  closely  connected  with  motor  reflexes 
perhaps,  are  inhibited.  Last  of  all,  as  a  rule,  the  auditory  sensations  seem  to 
disappear,  and  they  arouse  motor  activity  and  interfere  with  the  general  condition 
of  rest,  least  directly  of  any.  In  short,  the  content  of  sleep  consists  of  a  group 
of  sensations  of  "  fatigue "  or  "  rest."  Sleep  is  a  more  complete  rest.  The 
process  is  a  dominance  of  an  organized  group  of  these  sensations.  Such  sen- 
sations from  one  part  are  associated  with  those  from  another.  It  is  not  that  the 
sensations  are  only  aroused  at  the  time  of  sleep,  of  course,  but  that  they  become 
dominant  in  attention  as  any  other  group  of  experiences  may  be  dominant  in 
attention.  This  dominance  is  promoted  by  the  intensity  of  the  sensations  them- 
selves and  by  other  conditions  of  attention. 

That  the  intensity  of  sleep  tends  toward  a  maximum  some  time  after  sleep 
begins,  may  be  analogous  to  the  inertia  of  attention  to  other  things.  After  two 
or  three  hours,  sufficient  waste  products  may  be  thrown  off,  that  there  is  less 
actual  stimulation  of  fatigue  sensations,  and  less  resistance  to  disturbance  by  other 
processes.  But  the  relatively  small  value  of  sleep  broken  up  in  short  periods, 
suggests  that  the  real  anabolic  processes  do  not  become  very  effective  until  after 
this  time.  Over-fatigue  may  be  injurious  to  sleep,  to  be  sure,  but  because  of  the 
mental  excitement  or  because  the  excited  condition  of  the  muscles  continues  to 
arouse  strain  and  pain  sensations,  and  prevent  relaxation.  Lastly,  learning  to 
sleep  in  a  position  involving  strain  of  some  set  of  muscles  seems  to  mean  the  form- 
ing of  an  association  between  the  strain  and  a  condition  of  rest  of  other  parts. 
Naturally  such  sleep  is  not  so  beneficial. 

Under  such  conditions  of  inhibition  by  a  group  of  sensations  of  rest,  what 
other  processes  do  arise  and  constitute  dreams,  will  of  course  have  the  uncertain 
and  little  controlled  character  of  the  "  fringe  of  consciousness  "  when  attention  is 
nearly  dominated  by  any  other  set  of  experiences.  Naturally  also,  they  will  tend, 
as  the  facts  cited  in  the  second  chapter  suggested,  to  prove  a  disturbance  of  sleep, 
not  an  organic  part  of  it. 

The  muscular  relaxation  and  inhibition  of  elaborate  cerebral  and  other  nervous 
activity  leads  to  a  removal  of  much  of  the  sensory  stimulation  of  the  vaso-motor 
center  and  a  consequent  tendency  to  relaxation.  The  brain  vessels  under  the 
influence  of  this  stimulation  have  remained  constricted  during  the  waking  condi- 
tion nearly  to  the  limit  they  are  capable  of,  and  show  the  most  marked  and  con- 
stant relaxation  with  sleep.  If  any  special  utility  is  to  be  assigned  to  this  fact, 
it  may  be  that  the  effective  building  up  of  energy-giving  substance  in  the  brain 
requires  greater  circulation  than  is  demanded  by  other  parts.  Professor  Lombard 
has  suggested  that  the  constriction  with  waking  condition  may  be  protective, 
preventing  too  much  compression  of  cerebral  cells  by  higher  blood-pressure. 
During  sleep  this  is  unnecessary  and  we  find  relaxation. 


GENERAL  CONCLUSIONS  AND  THEORY  79 

This  relaxation  apparently  tends  to  bring  with  it  a  decrease  of  breathing 
activity  at  first,  which  gives  too  little  ventilation.  This  would  probably  stimulate 
all  the  centers.  The  first  type  of  breathing  would  be  a  result  of  the  attempt  of 
the  vaso-motor  and  breathing  centers  to  adjust  themselves  to  each  other  with 
relaxation  of  the  vaso-motor,  and  to  the  carbon-di-oxide  content  of  the  blood. 
In  this  adjustment,  it  seems  to  be  the  chest  that  takes  up  the  activity  mainly; 
there  remains  a  decreased  abdominal  breathing.  Possibly  we  might  assume  that 
the  chest  and  abdominal  breathing  are  controlled  by  different  parts  of  the  respira- 
tory center,  and  that  the  part  which  controls  the  chest  is  not  so  near  the  vaso- 
motor center  as  that  which  controls  the  diaphragm,  and  not  so  much  influenced  by 
the  vaso-motor  relaxation. 


APPENDIX 

THE   INFLUENCE   OF   SOME   DRUGS    UPON    THE   CIRCULATION    DONE   IN 
COOPERATION  WITH  CORWIN  S.  CLARKE,  M.D. 

In  these  experiments  the  attempt  was  made  to  use  the  methods  which  have 
been  developed  in  the  study  of  the  circulation  and  sleep  to  investigate  the  effect  of 
certain  drugs  upon  the  circulation.  The  subject  was  a  young  man  who  had 
recently  undergone  a  Gasserian  ganglion  operation,  the  trephine  for  which  was 
through  the  front  part  of  the  left  temporal  bone.  The  form  of  the  pulse  through 
this  trephine  has  already  been  referred  to,  in  the  chapter  on  pulse  form. 

The  first  form  of  brain  plethysmograph  (cup  covered  with  thin  rubber  to 
which  a  cork  plate  is  attached)  was  used  in  all  tests  with  this  subject.  New  cork 
plates  were  made,  of  course,  to  fit  the  trephine.  The  edges  of  the  instrument  were 
held  firmly  against  the  bone  by  means  of  a  broad  bandage  tied  horizontally  around 
the  head.  The  cavity  of  the  cup  was  connected  to  the  largest  size  of  piston 
recorder.  No  tests  were  made  of  the  influence  of  the  scalp  circulation  on  the 
record,  since  the  experiments  with  the  first  and  second  subjects  had  shown  that 
the  pulse  and  changes  in  the  scalp  are  negligible  in  comparison  with  those  in  the 
brain.  The  principle  of  the  Hallion-Comte  plethysmograph  was  used  to  record 
the  hand  volume.  The  bulb  was  connected  to  a  medium-sized  piston  recorder. 
The  chest  breathing  was  recorded  by  a  Marey  pneumograph  connected  to  a  Marey 
tambour.  In  all  this  work  the  subject  was  sitting  up,  and  was  in  another  room 
on  the  opposite  side  of  the  wall  from  the  recording  apparatus.  Dr.  Clarke  gave 
the  stimuli,  and  also  pressed  a  key  which  indicated  on  the  drum  places  where  a 
significant  report  was  to  be  made. 

On  account  of  the  hesitancy  of  the  subject  to  take  the  drugs,  only  a  few 
experiments  could  be  performed.  Two  tests  were  made  with  amyl  nitrite,  one 
with  nitroglycerin,  and  one  with  adnephrin.  We  shall  next  reproduce  and  describe 
the  results  with  amyl  nitrite. 

K.,  November  25,  I  (Fig.  80,  Plate  62). — The  diameter  is  multiplied  by  three- 
fourths.  The  curves  from  the  top  down  are  the  chest  breathing,  the  indicator 
line,  the  hand  volume  and  the  brain  volume.  A  portion  of  the  breathing  curve  at 
the  start  was  lost  because  the  tambour  was  not  pressing  firmly  enough  on  the 
paper.  At  a,  the  glass  bulb  was  broken  and  the  subject  began  to  breathe  the 
amyl  nitrite.  At  2',  the  subject  said,  "  Pretty  near  done  with  that  one.  Doctor?" 
Dr.  Clarke  reported  that  his  breathing  was  labored  as  if  excited.  At  b,  the  nitrite 
had  become  practically  exhausted,  and  the  bulb  was  removed.  At  5,  the  subject 
made  a  remark.  At  4  and  5,  he  swallowed.  It  will  be  seen  that  the  brain  volume 
began  to  rise  after  a  few  pulse-beats  and  was  dropped  twice  artificially.  The  size 
of  pulse  from  the  brain  also  became  larger.     Counting  the  number  of  pulses  in  a 


INFLUENCE  OF  DRUGS   UPON  THE   CIRCULATION  8i 

given  space,  shows  that  the  heart-rate  increased  rapidly.  This  may  be  respon- 
sible for  a  hyperdicrotic  pulse  in  the  hand  at  times  later  in  the  record.  Just 
before  c,  the  low  position  of  the  dicrotic  in  the  hand  curve  without  a  correspond- 
ing volume  or  heart-rate  change,  indicates  that  the  blood-pressure  has  fallen 
distinctly.  At  c,  a  very  marked  rise  in  the  hand  curve  began.  The  needle  was 
dropped  several  times  artificially.  In  spite  of  the  low  dicrotic  in  the  hand  at  c, 
the  secondary  waves  in  the  brain  pulse  seem  to  be  somewhat  higher  at  this  point, 
although  the  pulse  form  is  not  clear.  The  brain  volume  reached  its  crest  just 
after  2'  and  began  a  rapid  fall  with  decreasing  size  of  pulse.  The  sudden  rise  in 
the  brain  at  e  is  doubtless  due  to  movement;  that  at  d  may  be.  The  rise  of 
volume  in  the  hand  continued  irregularly  until  e.  After  e  the  hand  curve  fell 
rapidly,  while  the  fall  in  the  brain  had  become  comparatively  slow. 

K.,  November  25,  II  (Fig.  81,  Plate  63). — The  order  of  the  curves  is  the 
same  as  in  the  preceding  extract.  The  nitrite  was  given  from  a  to  b.  In  break- 
ing the  glass  bulb  a  loud  noise  was  made  and  the  subject  jumped.  This  is  prob- 
ably responsible  for  the  break  in  the  brain  record.  At  5i,  5,,  53,  6,  7,  8  and  some 
other  points  the  subject  swallowed.  But  such  acts  seem  to  have  no  effect  upon 
the  circulation  curves.  The  breathing  became  slower  and  deeper.  The  heart- 
rate  was  increased  considerably.  The  brain  volume  began  to  rise  soon  after  the 
stimulus  began,  the  curve  was  dropped  twice  artificially,  and  reached  its  crest 
at  about  the  time  the  stimulus  ceased  at  b.  After  the  first  part  of  the  rise,  the 
pulse  became  smaller  from  the  brain.  This  probably  indicates  a  plugging  of  the 
trephine  as  in  cases  found  during  sleep.  During  the  fall  after  the  crest  in  the 
brain,  the  pulse  first  became  larger  and  then  smaller.  The  brain  and  hand  curves 
interfered  under  5,  and  were  changed  artificially.  The  rise  with  larger  pulse  in 
the  hand  did  not  begin  until  c  and  reached  its  crest  at  6,  again  distinctly  later 
than  the  crest  of  the  brain  curve.  The  change  in  the  dicrotic  in  the  hand  pulse 
before  c  indicates  that  the  blood-pressure  had  already  fallen  markedly.  No  tests 
were  made  to  show  accurately  the  temporal  position  of  the  dicrotic  in  the  pulse 
wave.  But  in  the  original  of  this  record  as  accurate  measurements  as  possible 
were  made  on  the  scale  in  the  eyepiece  of  a  microscope  which  was  mounted  so 
that  it  could  be  moved  by  a  screw  adjustment.  The  distance  from  the  beginning 
of  the  pulse  to  the  dicrotic  was  measured.  This  distance  appeared  to  be  greater 
at  c  than  during  normal,  and  still  greater  towards  6,  a  result  with  lowered 
pressure.  Such  a  delay,  combined  with  a  more  rapid  pulse  would  lower  the 
dicrotic.  In  spite  of  this,  the  secondary  waves  in  the  brain  pulse  during  the 
period  of  high  volume,  occupy  a  relatively  high  position.  After  d  they  assume 
a  distinctly  lower  position.  It  is  not  so  clear  whether  a  similar  statement  would 
be  true  of  the  hand.  Such  a  high  position  of  the  secondary  waves  may  be 
explained  as  due  to  the  relaxed  vessels  and  decreased  reflection.  This  explanation 
is  consistent  with  the  theory  of  pulse  form  developed  on  pp.  75  ff. 

We  find,  therefore,  that  the  brain  volume  is  markedly  increased  under  the 
influence  of  amyl  nitrite,  in  spite  of  the  lowered  blood-pressure  which  the  drug 
brings  about.     The  brain  vessels  clearly  relax.     This  relaxation  begins  very 


82  STUDIES  IN  THE  CIRCULATION  AND   SLEEP 

quickly.  Relaxation  in  the  hand  begins  more  slowly,  but  the  high  volume  of  the 
hand  continues  after  that  of  the  brain.  The  quick  response  in  the  brain  is 
similar  to  the  quick  flush  of  the  face. 

In  the  test  with  nitroglycerin,  ^/^j^  gr.  was  injected  into  the  arm.  We  shall 
not  reproduce  the  entire  record  although  it  was  fairly  successful.  The  injection 
itself  acted  as  a  temporary  stimulus  of  course.  The  effects  of  the  drug  began 
before  the  stimulus  reaction  had  disappeared.  In  K.,  November  26,  II  (Fig.  82, 
Plate  63),  we  reproduce  a  section  showing  the  condition  before  the  stimulus  was 
given,  and  another  taken  from  near  the  end  of  the  record.  The  total  effect  had 
been  a  fall  of  about  3  cm.  in  the  level  of  each  circulation  curve,  which  change  had 
been  compensated  for  artificially.  The  size  of  pulse  from  the  hand  was  greatly 
decreased.  There  was  no  constant  change  in  the  size  of  pulse  from  the  brain. 
It  is  noticeable  that  in  the  first  extract  before  the  stimulus,  the  larger  pulse  occurs 
at  the  crest  of  the  Traube-Hering  wave  in  the  brain,  while  in  the  second  extract 
the  larger  pulse  is  at  the  trough  of  the  Traube-Hering  wave ;  but  without  a  con- 
tinuous blood-pressure  record,  it  would  be  useless  to  try  to  explain  this.  The 
dicrotic  was  unusually  low,  and  the  pulse  unusually  fast  in  the  first  extract ;  the 
dicrotic  was  still  lower  in  the  second.  Mentally,  the  subject  was  excited  at  the 
start  by  the  idea  of  the  injection  coming,  and  this  probably  modified  the  reaction. 

It  is  to  be  regretted  that  we  have  only  one  partially  successful  record  of  nitro- 
glycerin. The  difference  in  the  reaction  to  amyl  nitrite  and  nitroglycerin  seems 
to  be  striking  and  is  of  importance.  But  the  results  with  nitroglycerin  are  not 
so  certain  as  those  with  amyl  nitrite. 

The  adnephrin  was  given  through  the  mouth.  The  result  was  not  very  definite, 
but  there  was  apparently  a  rise  in  volume  of  both  brain  and  hand.  The  record 
was  not  successful  enough  to  reproduce. 


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KoHLSCHUTTER.    Messungcn  der  Festigkeit  des  Schlafes.    Zeitsch.  f.  rationelle  Medicin,  Bd. 

17,  1863,  p.  209. 
KoHLSCHUTTER.     Mechanik  des  Schlafes.    Zeitsch.  f.  rationelle  Medicin,  Bd.  34,  1869,  p.  42. 
Lombard  and  Pillsbury.     Secondary  Rhythms  of  the  Normal  Human  Heart.    Amer.  Jour. 

of  Physiol.,  Vol.  Ill,  1899,  p.  201. 
Mays.    Uber  die  Bewegungen  des  Menschlichen  Gehirns.    Virchow  Arch.,  Bd.  88, 1882,  p.  125. 
MiCHELSON.    Untersuchungen  iiber  die  Tiefe  des  Schlafes.     Psychol.  Arbeiten   (Kraepelin), 

Bd.  2,  p.  84. 
Mosso.    Uber  den  Kreislauf  des  Blutes  im  menschlichen  Gehirn.    Leipzig,  1881. 
Von  Recklinghausen.     Uber  Blutdruckmessung  beim  Menschen.    Arch.  f.  exp.  Pathol,  u. 

Pharmakol.,  Vol.  46,  1901,  p.  78. 
Von  Recklinghausen.    Unblutige  Blutdruckmessung.    Ibid.,  Vol.  55,  1906,  pp.  375  and  412. 
Shepard.     Organic  Changes  and  Feeling.    Am.  Jour.,  of  Psychol.,  Vol.  XVII,  1906,  p.  522. 
Wiggers.    Action  of  Adrenalin  on  the  Cerebral  Vessels.    Amer.  Jour,  of  Physiol.,  Vol.  14, 

1905,  p.  452. 
Wiggers.    The  Innervation  of  the  Cerebral  Vessels  as  Indicated  by  the  Action  of  Drugs. 

Amer.  Jour,  of  Physiol.,  Vol.  20,  1907,  p.  206. 
Wiggers.     Some  Vasomotor  Changes  in  the  Cerebral  Vessels  Obtained  by  Stimulating  the 

Carotid  Plexuses.    Amer.  Jour,  of  Physiol.,  Vol.  21,  1908,  p.  454. 


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CLINICAL   PSYCHIATRY:    A  Text-Book  for  Students 
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REST  AND  PAIN 

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THE   MAJOR  SYMPTOMS  OF  HYSTERIA 

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